Schiit Audio Aegir power amplifier

Class-D audio amplifiers: What's the argument for them? Class-A audio amplifiers: What's the argument against them? Class-AB amplifiers: Why does everybody make them? Each of these amplifier output architectures has strengths and weaknesses. Each will interface more or less successfully with a given loudspeaker in a given room. Each has a distinctive sonic signature. Consequently, as knowledgeable audiophiles with a laundry list of system-building goals, we are required to choose the amplifier type that best suits our speakers, our room, and our individual musical-aesthetic predilections.

So: To set the stage for my descriptions of Schiit Audio's new Aegir power amplifier ($799), I must begin by summarizing my empirical observations about the sonic qualities of the three most common output-section architectures: class-D, in which the conducting done by the output devices is related not to the angle (0° to 360°) of their input signal but to a fixed-rate pulse; class-A, in which the output devices conduct for the whole 360° of the input signal (and because the current going through the output device is related to its input voltage, we call this transconductance, abbreviated as gm); and class-AB amplification, in which transconductance occurs for more than 180° of the input signal but less than 360°.

Class-D creates a simulacrum of the original signal, which feels slightly spartan and texturally different than class-A or -AB. Class-D generates power easily into a wide range of speaker loads. It can be superdynamic. It appears cleaner and more transparent than class-A. Higher in contrast. Quiet passages and empty spaces can feel a bit electronic. Images are well-outlined but devoid of warm flesh. Voices and instruments display a saturated but distinctly limited palette of tones. The feedback and low-pass filtering required for class-D add hardness to the sound. The best-executed class-D amplifiers deliver music with a refined, grainless quality that many audiophiles find appealing.

919sch.bac

Class-A is naturally low distortion. Maximum information-density. Less distinctly drawn and impactful than class-D. More overtly textured, painterly, colorful, and full-bodied. Lower in contrast than class-D but with a wider, more complex palette of tones. Empty spaces seem charged and appear connected to performers. The lower feedback required to achieve linearity allows for a more supple and relaxed presentation. Properly executed class-A sounds trippy and lifelike.

Class-AB is a compromise that allows amplifiers to produce class-A power up to some predetermined bias point (typically no more than a few watts), at which point it crosses over to almost-class-B, thereby allowing more watts (of a reduced quality) before apocalyptic clipping sets in. Driving benign loads of reasonable sensitivity, class-AB amplifiers, especially some tube models, can and sometimes will sound superbly class-A-like. Hence their popularity.

But: What if I told you that the Schiit Audio dudes, Jason Stoddard and Mike Moffat, have devised an operating strategy, called Continuity, that gets you possibly all the benefits of class-A while avoiding some of its heat and efficiency issues?

As Jason Stoddard told me in an email, "Depending on your point of view, Aegir Continuity is either (a) a lower-power, higher-cost version of our Vidar amplifier, displaying Schiit's unquestioned engineering decrepitude, or (b) a really interesting way to get around the problems of transconductance droop and the mismatch between NPN and PNP output devices."

Schiit claims their Continuity output stage enables "class-A-like" performance up to the Aegir's full rated power. "Class-A-like" is an interesting description, but what does it really mean? According to Jason, "Continuity extends the benefits of class-A (linear transconductance) far past the class-A bias region. In theory, the Aegir should sound pretty much the same whether it is operating within its 10W of class-A bias or putting 100W into a 4-ohm speaker in mono.

"Continuity allows us to run more efficiently than class-A. It is not a panacea, it doesn't run cold, but half the standing current of a class-A design is a pretty decent reduction."

919sch.2

According to Jason, Schiit's Continuity circuit was derived from the work of super-smart amplifier-engineering mavericks Bob Cordell and John Broskie. Here's how my amp-designer friend J.C. Morrison (Silbatone) describes Bob Cordell: "There isn't a human alive that can research, measure, and explain what is or isn't happening in a circuit more thoroughly than Cordell. John Broskie is an extraordinary circuit-analyst—like Cordell—but also a historian. His blog is an international treasure for audio hardware engineering." (footnote 1)

Seems like those Schiit dudes hang with some sharp people!

The Aegir
The original Aegir was a Norse sea giant, but this one is extremely compact: a 19.6 lb, 9" by 13" by 3.9" stereo amplifier which, conveniently, is fitted to the same chassis as Schiit's lower-priced/higher-powered amp, the Vidar, which is named after a silent and reliable Norse god. According to the Schiit website, the Aegir is "a hot-running amp, with over 10W of Class-A standing bias." Beyond those all-natural class-A watts, the Aegir generates a total of 20Wpc into 8 ohms, doubling to 40Wpc into 4 ohms. Users may effortlessly convert their stereo Aegir to an 80W (into 8 ohms) monoblock by simply connecting the XLR output of a true balanced preamp to the single XLR input on the Aegir's rear panel.

The Aegir is made in California and, according to Stoddard, "employs a 100% discrete, fully complementary, current-feedback, linear power supply. And features intelligent microprocessor management of all critical operating conditions, including DC offset and standby mode, as well as relay-activated shutdown for overcurrent, thermal, and other faults."

With Wharfedale Lintons
While working on last month's reviews, I connected the Schiit Aegir to Wharfedale's $1198/pair 85th Anniversary Linton Heritage loudspeakers—and brother, oh brother! That sweet-sounding combo helped me remember why I hold the Stanley Brothers in such high lonesome reverence. The Stanleys' "Hard Times," from The Complete Mercury Recordings (44.1/16 FLAC Mercury/Tidal), reminded me what standing close to a full-tilt mountain band actually feels like. Think pure acoustic electricity! The Aegir lit up the Lintons and gave them delicacy and lucidity, with an undercurrent of strength.

919sch.4

The Aegir's ability to balance generous bass power with high levels of filigreed class-A detail made finger picks plucking banjo strings and wood bows rubbing fiddle strings into titillating physical pleasures. I could live, satisfied, forever with this reasonably priced pairing.

With Harbeth P3ESRs
If I could keep only one pair of all the stand-mount speakers I have stowed in my bunker, it would be the Harbeth P3ESRs. These small, finely crafted loudspeakers sound more right-of-tone and correct-of-balance than any other speaker I know. Therefore, I am always searching for the perfect amp to drive them—and damn, if the Schiit Aegir didn't wave an excited hand saying, "Pick me! Pick me!"

The Aegir made an excellent case for itself by how it reached in and exposed every tiny texture and spatial nuance of a very complex, difficult-to-reproduce recording: Cabaret Modern: Night at the Magic Mirror Tent (44.1/16 FLAC Harmonia Mundi/Tidal). Cabaret Modern is a sound-collage night at an imaginary nightclub, performed by French avant-garde guitarist/composer Noël Akchoté and a cohort of players. Inside the Magic Mirror Tent, I was treated to a full-on 1930s-style German cabaret, with drinking, spontaneous applause, sing-alongs, and stomping on a wood stage. Best of all, there is a band with an accordion, a harmonium, and a honky-tonk piano—all this mixed together with car sounds, doors slamming, and people talking. On the happy "Via Con Me," the performers were directly in front of me, in the front row by the stage. The Aegir made these divertissements feel solidly and effectively presented.


Footnote 1: Designing Audio Power Amplifiers, Bob Cordell's encyclopedic book on audio amplifier design, is now available in a second edition from Focal Press: .—John Atkinson
COMPANY INFO
Schiit Audio
24900 Anza Drive, Unit A
Valencia, CA 91355
(323) 230-0079
ARTICLE CONTENTS

COMMENTS
Anton's picture

Every once in a while, I will cross paths with a review that makes me wanna stop what I am doing, run out to a dealer, and impulse buy the product.

This is one of those times.

I am already trying to envision where I would put it!

I have a little loft above the barn with a pair of Heresy speakers and a pair of Infinty Intermezzo 2.6 speakers (purchased thanks to an ancient review from Stereophile!) that I am running with an Oppo 205 into an SMSL 98 dollar amp....and it sounds great. I'm thinking this piece of Schiit plus a home brew preamp a friend is building may be just the ticket...and affordable!

That's some good Schiit!

invaderzim's picture

It does get more dangerous when the items being reviewed are priced like this.
I like the looks, I like the size and I respect Herb's take on the sound.

Bogolu Haranath's picture

The least expensive Class-A amplifier in the Stereophile 2019 October recommended components list, Schiit Audio Aegir ($799) .......... That is excellence in engineering :-) .........

Bogolu Haranath's picture

May be HR could also review the new Schiit Audio Freya+ ($899) pre-amp? :-) ...........

Travis's picture

This review is confusing to me. What preamp were you using, the 5K RP-7? Also, when hooking up headphones to the Schiit, how did you control the volume level. It doesn't have volume control, does it?

Thanks.

Herb Reichert's picture

I used the Rogue Audio RP-7 preamp

it is a fairly neutral but also radiant-sounding hybrid pre with a low output impedance

hr

Bogolu Haranath's picture

Since HR mentions about hooking up the amplifier's speaker outputs directly driving the headphones, may be HR could review the RAAL SR1a ribbon headphones ($3,499), which are supplied with an amp/ribbon interface box ....... That interface box can be hooked up to an amp/integrated-amp speaker outputs :-) ........

Herb Reichert's picture

are on my head as I type this

herb

Bogolu Haranath's picture

Great ...... Eagerly waiting to read your (HR) review :-) ...........

JRT's picture

Benchmark Media AHB2 would seem to be a good amplifier for these RAAL SR1a headphones.

Bogolu Haranath's picture

Rogue Audio Sphinx (100 WPC) which HR used for comparison with this Aegir review, could also possibly be used for the RAAL review :-) ........

JRT's picture

First strike is that the Rogue Audio Sphinx lacks balanced/differential inputs with high CMR.

Second strike is that it is an integrated amplifier, which lacks flexibility in later upgrades to proper separate components with less compromised functionality.

Third strike is that they wasted resources on integrating a phono preamplifier instead of using those resources to add a couple of additional balanced inputs to connect an outboard phono preamplifier (and providing ability to later upgrade to a better phono preamplifier) located near the turntable, and to provide a tape loop with balanced I/O for recording the output of the phono preamp with a high quality outboard AD converter.

Bogolu Haranath's picture

HR usually reviews with several different amplifiers ......... Let us wait and see what HR says in his review of the RAAL headphones :-) ........

JRT's picture

I too am looking forward to reading your opinion on the RAAL SR1A.

My AKG K 1000 headspeakers also require a power amplifier suitable for driving loudspeakers, though mostly for the larger voltage swing. Those are 120_Ohm, so don't draw much current, but the low power sensitivity is such that each side needs 1_Wrms to deliver 105_dB, 11_Vrms across the load, 22_Vrms for +6_dB headroom.

Two key reasons that I bought my Audeze LCD-X and LCD-XC headphones are that they sound pretty good for what they are, for their type, and are easy to drive.

Bogolu Haranath's picture

May be HR could also review the new Revel Performa F226Be speakers ($7,000/pair) and compare them to some what similarly priced Harbeth M30.2 speakers, and many other bookshelf/stand-mount speakers and floor-standing speakers in this price range :-) .........

terzinator's picture

I'm with the others who have read the review and are itching to go out and get an Aegir -- or two!

Given the Harbeths' low sensitivity, would you recommend using a pair Aegirs as monoblocks? Or fine as a stereo amp? (Not a big room, and not super loud.)

Ortofan's picture

... Parasound NewClassic 2125 v.2.
150W/ch into 8Ω, 225W/ch into 4Ω and 400W bridged mono into 8Ω or 4Ω.
https://www.parasound.com/2125-v2.php
https://www.audioadvisor.com/prodinfo.asp?number=PAC2125V2

tonykaz's picture

----- "Best attainable sound for a component of it's kind, almost without practical considerations, with the least musical compromise" -----

I can trust Mr.HR on this, I've owned Schiit since 2011.

Schiit under-rate themselves, they underpromise yet they over deliver in performance and build quality.

They STILL put the dam power switch on the dam BACK of their devices where it's nearly impossible to reach if a person has special physical limitations . I have an outboard Levitron Illuminated Power Switch to easily control my Schiits and am envious of folks that have front chassis Power Switches ( like all normal people have ) dammit!

But...

Schiits perform like Great Voices in Opera: Joan Sutherland & Pavarotti

There might be equally great gear out there.

There might be an equally great Company out there.

But they're rare.

PS Audio comes to mind.

I keep reading Stereophile for another Outstanding Discovery like this one that our Tyll & Steve G gave to me at RMAF 2011.

Tony in Venice

ps. I'm suggesting that our Mr.HR is a Class A Recommended Audio Writer & Philosopher

Jim Austin's picture

>>ps. I'm suggesting that our Mr.HR is a Class A Recommended Audio Writer & Philosopher

I agree. Good observation.

Jim Austin, Editor
Stereophile

tonykaz's picture

I was holding back a wee bit.

This issue has 5 outstanding pieces including two from HR, the AWSi, the Barton/ John Atkinson piece, and the Cary story.

I don't read or comment on any of the Phono pieces.

Back in the Day, early 1980s, I imported and sold British HiFiN&RR Subscriptions to our American Customer Base. I did this because it was the finest Audio Mag. ( I thought ). HP was somewhat inspired writing so I sold TAS as well. I advertised in Audio Mag. Writing, back then, was somewhat useful but lacking insight.

Since around 2011 when I returned to paying attention to Published Audio, Tyll, Steve G and Bob Katz and all things digital it became obvious that no Company ( like our IVOR at LINN ) had any sort of grip on Audio Press leaving JA a hand to encourage un-hindered brilliance which showed up in the form of Tyll Hersten ( and his pals ). Phew!!!

Now, look at all the greatness migrating to Stereophile for a few thousand words ( beautiful voices in a World of Corporate Censorship ). I look around and don't quite find much interesting reading in concentrations like is flowing out of Stereophile today.

Stereophile has become the finest Audio Publication in my memory.

Nice work Mr.Jim Austin

Tony in Venice

ps. I pass-on my Stereophile Magazines to my new One Barber, barber Shop where they end up getting seen by a hundred "heads" per week, it's probably the most well-read Magazine in Venice.

Bogolu Haranath's picture

Jim Austin is the perfect person to review the relatively new JBL Synthesis S4700 floor-standing speakers ($15,000/pair) :-) ..........

Ortofan's picture

... Pavarotti, then I'll wait for one that sounds like Carlo Bergonzi.

Bogolu Haranath's picture

That one got to be the D'Agostino Relentless mono-blocks :-) .........

tonykaz's picture

Why only one?

or

are you one of those Mono people ?

tony in venice

Bogolu Haranath's picture

I said 'mono-blocks' ...... that is two for stereo :-) ..........

tonykaz's picture

Yea, you did, you're right, : BLOCKS not block !!!

I was just being silly

I didn't give this it's proper deserving thought.

Besides, those big Amps come in boxes that cost more than the Amplifier contained, making them Show-off Status & Ego type products.

They are great Amps but are they an improvement over a 1985 vintage Threshold Amp?

Tony in Venice

ps. Mr.D'Augustino is the Jeweler of Audio Gear

ps. the little Schiit Amp could be dressed up a bit by a Fab Shop doing Show Display Products.

tonykaz's picture

No Problem,

you can find his Voice by changing Tubes in your Valhalla 2 Preamp.

Tony in Venice

ps. might help to have access to a bit of wacky tobaccy .

Bogolu Haranath's picture

You mean 'wacky tobacky'? :-) .........

dial's picture

The Parasound is only 600 $ but no XLR. In the future, everything'll be class D. In France, they have the 3 D LABS NANO AMPLIFIER, 250 W per channel, also bridgeable, but 1630$. Not so many D Amps. It's a power amp too.
I don't like integrated amps (like JRT) : a lot of people don't use phono anymore (sad but true) but if they want they surely buy a separate RIAA preamp, from 20 to 20 000$. The sound can only be better than the phono boards in the pres sections. I've listened to an Atoll with phono and with their phono box, the box was way better, although it's the same circuitry.

jeffhenning's picture

...the preferred amp for the Raal headphones by their designer. Read about that here:

https://6moons.com/audioreview_articles/raalrequisite/

https://6moons.com/audioreview_articles/benchmark/

jeffhenning's picture

...it would be fantastic if the made a simple 100 watt mono block. Not a stereo that bridges to mono.

In their line up, they have this model and another that is a stereo model that bridges to 400 watts. Neither really hits that sweet spot for my system since I have a pair of Rythmik servo subs that handle everything below 150Hz. I just don't need more than 100 watts for KEF LS50's across the front

I could use this amp quite well, but it's a gigantic power hog that can help heat a small room. Schiit makes no bones about this thing running hot at idle. It pulls up to 450 watts from the wall socket. Its efficiency is incredibly low. For my purposes, this won't do.

I'm looking for a mono block to power my center speaker and not waste a ton of energy or have 400% more power than necessary.

I noticed that a few companies in Europe now offer custom nCore and Purifi mono blocks for very reasonable prices.

I guess that's my route for a center channel amp.

Bogolu Haranath's picture

Check out the PS Audio Stellar stereo or mono-blocks (Stereophile Class-A) or the Mytek Brooklyn Class-D amps (reviewed by Stereophile) :-) ..........

Ortofan's picture

... what is your objection to a two-channel amp running in bridged-mono mode?

jeffhenning's picture

Nothing wrong with a bridged mono block if you need 300 or 400 watts. Or wrong with it period.

I need around 100 watts to drive a KEF LS50 center channel. I could use a 400 bridged mode amp, but I'd be wasting money on the amp and money on the electricity to run it.

The LS50's can't really play any louder than 105dB (20dB louder than their 85dB@1 watt specification).

Again, this is for a center channel in a theater set up with two 12" servo subs (soon to be four subs).

Bogolu Haranath's picture

Why not try a low power output home theater receiver? ........ Several companies sell such receivers, which cost less than $1,000 :-) ........

Bogolu Haranath's picture

Denon HEOS AVR ($599) receiver is one such example :-) ........

Ortofan's picture

... has a 200W output rating and is priced at $399.
https://www.outlawaudio.com/products/2200.html

bikerider1001's picture

How did you do it?

Travis's picture

like to know.

Herb Reichert's picture

in greater detail how to connect headphones to power amplifiers in my next Gramophone Dream were I discuss Grado's flagship headphone: the GS3000e and the Feliks Euphoria headphone amp.

the short version is you need a set of 4-pin XLR to banana cables.

Plus you got to stay cool, pray for grace, and turn the volume up s l o w l y.
thank you for reading my stories
stay tuned,
herb

Bogolu Haranath's picture

May be HR could review the relatively new Denon HEOS Class-D, Wi-Fi and Bluetooth capable integrated amp ($499)? :-) .........

Travis's picture

Love you and love your write ups.

Still can't find those volume pots on that Schiit power amp. I look forward to your next column, especially since I am a Grado fan man.

Bogolu Haranath's picture

May be HR could also review the Manley The Absolute Headphone Amplifier ($4,500)? :-) ..........

joemariano's picture

As always, a really nice review from Herb!!!!! He always makes me want to buy more equipment. I too own Harbeths! :D And good to see Stereophile covering product that us mortals can afford. Schiit is such a rebellious company.

Talking of rebellious, I’m curious to learn what new editor Jim Austin thinks about Stereophile’s sister site Inner-Fidelity using a Schiit employee to do “reviews” and “Canjam reports”?

tnargs's picture

....you should have let go along with Joe Roberts. You peaked early with Casual Reactions, which was entertaining in its day.

But these days, most well-informed audiophiles don't fall for the spiel that amps have all these magical properties (other than hypnotically induced by the sales pitch coming from salesmen and reviewers), nor generic sonic attributes based on classification. Stuff like "spaces sound electronic" and "trippy and realistic".... let's hope that most readers aren't buying it. Not anymore.

And remind me never to reference anything you ever write about the technical side. Poor Bob Cordell, champion of Class AB MOSFET amps, finding himself referenced in a review of an essentially Class A BJT amplifier (with 3 dB of class B headroom and a "secret squirrel circuit" probably error correction applied to flatten the transconductance curve). My informed guess is that Cordell would probably argue that the topology, component choices and circuit gimmicks of the Aegir are completely unnecessary and have more negatives than positives.

cheers

georgehifi's picture

Great "little" amp, but why didn't Schiit make both this Aegir and the Vidar the exact same gains.
So that on bigger bi-amp'able speakers the Aegir could be used where it's best on the mids and highs and the Vidar on the bass, without any need for a gain matching passive volume control involved??

Shiit!!! bring out a MkII Aegir before it's too late with the same gain as the Vidar, and if mkI Aegir customers want, re-call the original to change the gain for a small fee???

Cheers George

jma78's picture

I bought the Aegir based on reviews, together with Freya + . They sound great. However, the Aegir has a 60hz like humming noise from the unit as well as going to the speakers. I tried only connecting the power cord to it (no interconnect, no speaker cables, etc), it still has the humming noise from the unit. Went through psAudio's page for getting rid of humming noise, it does not work for me. https://www.psaudio.com/ps_how/how-to-find-and-fix-hum/
I guess it's due to the quality of the transformer. The sound is not too loud, and might not bother much. But still, I decided to return them.

I hope they can provide better quality transformers and add cost to the price.

It does not feel right as they say the transformer is made in California, and yet the quality is inferior than transformers made elsewhere.

Other observations
- Aegir back panel has too little space to work with. I hope plugs are spaced further apart.
- Freya + runs very very hot, the panel is almost untouchable, and the hottest area is above the transformer, not around the tubes. It's hotter than the Aegir.
- The Freya + has a 128 step stepped attenuator. When using remote or turn manually, it seems has 3 clicks sound every time. I wonder if it goes 3 steps a time or just the sound, or it's just hard to make it one step / one click.

Update 1:
A day later, when I hook them up for last listening before sending them back. The right channel of Aegir is dead. Right channel SE plug had contact issue when I first setup them up, I had to push the plug in harder to make it work. I will not buy their product until I hear some news on quality improvement.

I also contact the brand about the issue I encounter besides a different email of return request. They responded with a return auth code but no other information. Now I got two emails from them for return auth code.

Schiit sounds like a really bad brand name when I have trouble with the product. Not funny.

JRT's picture

"Schiit sounds like a really bad brand name when I have trouble with the product. Not funny."

That seemed quotable, and maybe a little more funny if not the one suffering the trouble with the Schiit product.

georgehifi's picture

If it's physical noise from the actual amp, then that's an issue if too loud for you, Class-A amp do stress the transformers a little and they will hum sometimes, but if it's quite and you have to put your ear to it don't worry, big Krells do it too.

If the hum is from the speakers you could have an "earth loop" I believe only one piece of equipment should be earthed in the chain (with me it's the amp/s), and everything else feeds off that via all the interconnects. You could use earth cheater plugs and "leave one piece earthed" always.

https://images-na.ssl-images-amazon.com/images/I/81n1JAlgfvL._AC_SL1500_.jpg

Cheers George

sharbatgula's picture

As an engineer in electronics I very well understand the classes of operation of the output stages and all the intricacies of the crossover region, the feedback, complementary components matching matching, efficiency, etc.
But boy is this is the right dosage of just enough technical terms and meaningful language for subjective description of the aural quality.

Bravo Mr.Reichert!

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