Cary Audio SLI-100 integrated amplifier

My Russian neighbor's blind grandfather, Vlad, has very discriminating ears—but only when I tell him what to listen for. If I don't, he just bitches about my choice of music. And he refuses to listen to "weak" American orchestras.

Not surprisingly, Vlad worships Mikhail Glinka. "Herb! Play Russlan and Ludmilla!" When he asks for "Pyotr Ilyich," I groan and quietly put the vodka back in the freezer.

A week ago, after an intense back-and-forth about Stravinsky, Leonard Bernstein, Sergei Diaghilev, and the Ballets Russes, I persuaded Vlad to perform a blind comparison of two fairly similar push-pull tube amps: Rogue Audio's Stereo 100 power amp ($3495), which uses KT120 tubes to output 100Wpc, and Cary Audio's new SLI-100 integrated amplifier ($5995), which uses KT150 tubes to produce 100Wpc.

Through the Harbeth Monitor M30.2 speakers I played Stravinsky's fierce mystery The Rite of Spring, in a recording by Valery Gergiev conducting the Kirov Orchestra (16-bit/44.1kHz FLAC, Decca/Tidal). I asked Vlad to tell me which amp—both operating in Ultralinear mode—reproduced Stravinsky with the greater ease and power.

Vlad jabbered for a couple of minutes—he didn't seem to be focusing. Eventually, he got into it. After the Sacrificial Dance, I stopped and forced him to commit. Vlad swore on Trotsky's grave that the second amp I'd played (the Cary SLI-100) was "more smooth and clear—just leave it—don't change anything!" I was pleased. And, of course, the Russian Grandfather approved of Gergiev's distinctly macho rendering of The Rite—"not like that messy Bernstein one!" Vlad knows that I favor Leonard Bernstein's more poetically evocative interpretation with the New York Philharmonic, especially on "six-eye" vinyl (LP, Columbia Masterworks MS 6010).

The Cary Audio SLI-100 ($5995) is an all-tube, stereo integrated amplifier that looks massive and businesslike. It's finished in what appears to be an extremely durable, black, crinkle powder-coat with a large blue-and-white Cary logo stenciled atop its 8.8-lb tube cage. The SLI-100 measures 17.25" W by 7.8" H by 16" D and weighs 42 lb without tube cage.

On the SLI-100's rear panel are four pairs of single-ended line-level inputs (RCA), and right- and left-channel pairs of five-way binding posts for speaker cables. Adjacent toggle switches let you select between the 4 and 8 ohm taps on the output transformer's secondary winding. A fifth pair of RCA jacks is labeled Subwoofer Output.


The front panel is simple: At far left is a Power button illuminated by a blue ring. To its right is a smallish, four-position Input knob. The big center knob is for Volume, and to its right is a small Balance knob (I love a balance control). Farther right is a ¼" headphone jack, and farthest right is another blue-ringed button that conveniently switches the SLI-100's output between headphones and speakers.

Under the tube cage is Cary's signature array of transformers and tubes. Instead of vintage-looking KT88 output tubes, as in Cary's 80Wpc SLI-80 integrated, the 100Wpc SLI-100 sports modern-looking KT150s to squeeze another 20W of Ultralinear power into 8-ohm loads. (Strangely, while the SLI-80 has a switch that lets the user toggle between Triode and Ultralinear operation of its output tubes, the SLI-100 is Ultralinear only.) The SLI-100's KT150s operate in class-AB1 with a fixed bias, and, according to the SLI-100's webpage, with only 4dB of global negative feedback!

A few days after my night with Vlad, I thought, Damn! The blind Russian really nailed it. This thing sounds clear and nonmechanical.

Then, in preparation for writing this review, I studied that webpage. I discovered that the SLI-100 splits the signal phase for its push-pull output stage in a way hardly anyone uses anymore: the "split load" or cathodyne phase inverter. Even more than interstage transformers, I prefer the sound of split-load inversion because I believe I can feel its superior balance. I also believe that this better balance translates into what Vlad said: "more smooth and clear." To my ears, split loads sound more relaxed and flowing than the long-tailed pair/dual-differential stages used in almost every other tube amp.


I read further, and noticed something else that probably contributed to my and Vlad's impressions of more clear and smooth. The SLI-100's voltage amplifier stage has a shunt-regulated push-pull (SRPP) architecture, but instead of the ubiquitous high-mu 12AX7 twin-triode tube, which is very low in transconductance, it uses the medium-mu, high-transconductance 6DJ8/6922—a nine-pin twin-triode tube (footnote 1) originally championed by Mike Moffat (formerly of Theta Digital, currently of Schiit Audio) and Roger A. Modjeski (of Music Reference/RAM Labs).

For our purposes here, it will suffice if you think of tube mu as a voltage-in/voltage-out ratio, and of transconductance as a tube's sensitivity to small-scale signal fluctuations. High-mu, low-transconductance tubes like the 12AX7 are efficient voltage amplifiers, but to my ears tend to generalize, simplify, and skip or jump over small-scale signal information. In contrast, the transconductance of a 6DJ8 (11,000 micromhos) is almost 10 times that of the 12AX7 (1200–1600 micromhos), and, to my ears, transmits 10 times more texture and inner detail. The SLI-100's 6DJ8 SRPP voltage amplifier is likely stable, quiet, and linear—but its sonic effect is like listening through an aural magnifying glass to instrument strings, vocal cords, and piano soundboards.

In evaluating an audio component, sequence is everything. Last month I wrote quite favorably about the above-mentioned Rogue Stereo 100. I'd had no previous experience at home with the amp's KT120 output tubes, but ended up being impressed by the Stereo 100's enjoyably neutral sound, especially in Triode mode from its 4 ohm taps. When I boxed up the big, black, 60-lb Rogue and installed Cary's big, black, 50.8-lb SLI-100, I naturally wondered how similarly or differently they'd sound.

My formal comparisons began with "Allein! Weh, ganz allein! (Alone! Woe, all alone!)," an aria from Richard Strauss's opera Elektra, with Birgit Nilsson in the title role, and Georg Solti conducting the Vienna Philharmonic (24/96 FLAC, Decca/Qobuz). I know Diana Krall and Joni Mitchell sing beautifully, but if you want to know if your hi-fi is really worth its full price, feed it something more demanding: like Nilsson singing Strauss. With only a day of break-in hours, the Cary SLI-100, driving the relatively insensitive (83dB/W/m) Harbeth P3ESRs from its 4-ohm taps, got me totally by the ears and started rearranging my audio-critical chromosomes.

The sound was both precise and easy flowing. Unfortunately, the little Harbeths choked noticeably in the high-energy, low-frequency opening, and gurgled some in the ensuing deep-bass passages. But O mein Gott! Nilsson's irresistible powers throttled my soul, as Strauss's opera force-fed high Teutonic sentiment and Reactionary Modernism directly into the dark parts of my mind.

Above 100Hz, the shoebox-sized Harbeths generated a smoothness and richness of tone that well expressed the poetic abilities of Strauss and Nilsson, but not the artistic and sonic force of Strauss's Elektra. At low volumes (below 90dB peaks), Birgit Nilsson's top octaves (the ones she owns) were exemplary in texture and tone. That was nice, but I wanted more Strausskraft!

Needing to hear what I was missing with the P3ESRs, I swapped in Harbeth's larger two-ways, the Monitor M30.2s. Voilà! Having more clean energy in the 50–100Hz octave made a HUGE difference. More cone area and box volume made more bass, which in turn made bigger images in a bigger space, with more copious room tone. Into the M30.2s, the Cary integrated's 100Wpc seemed more forceful than the Rogue amp's 100Wpc. A difference in power-supply topology? This fine 1967 opera recording by Decca/London is by necessity big and powerful; the Cary SLI-100 and Harbeth M30.2s sailed easily, sang beautifully, and made timpani poundings something to look forward to.

Comparison: Pass Laboratories XA25
For me, the most important part of critical listening is to notice where the music directs my attention. When I installed Pass Laboratories' XA25 power amp ($4900), which puts out 25Wpc into 8 ohms, the first thing I noticed was how "tightened-up" Stravinsky sounded. Low-frequency strings had more size and power. Clarity improved. I also noticed how the soundstage was reduced by about 15% in all three dimensions.

Footnote 1: In vacuum tubes, to quote Wikipedia, "transconductance . . . is typically defined as the change in the plate (anode)/cathode current divided by the corresponding change in grid/cathode voltage, with a constant plate (anode)/cathode voltage." For example: a 12AX7 tube will vary about 1mA per volt of signal; a 6DJ8 tube varies 10mA for the same volt.
Cary Audio
6301 Chapel Hill Road
Raleigh, NC 27607
(919) 355-0010

Bogolu Haranath's picture

I'm waiting for a comparison follow-up review between Cary SLI-100 and Cambridge Edge A .......... The only thing common I can find between the two is, both company names start with the letter 'C' :-) ...........

Bogolu Haranath's picture

Ok ...... They both are rated 100 WPC/8 Ohms and, they both have headphone outputs :-) ........

Bogolu Haranath's picture

I'll bet either a 'White Russian' or a 'Black Russian', those are the only common things between the two :-) ........

anthony.aaron47's picture

"I like connecting headphones directly to the speaker binding posts on the backsides of power amplifiers."

So, just how does one do this? I've never heard of it … I've got a 2A3C integrated amp with 4 and 8 ohm taps.

Bogolu Haranath's picture

HR describes how he does it in more detail on AudioStream website ......... Look for HR's article on 'loudspeakers' on AudioStream with comments :-) ............

kinalwyesset3's picture

Great review! If you're looking on a solid, reliable, and durable high-end speakers, you should check out ArtisanAcoustics – Their speakers sound so good, and are reasonably priced for what you get. You'll thank me for this. Cheers!

Ortofan's picture

... rather high levels of noise and distortion, a frequency response that is far from flat when driving a typical speaker load and that has at least one tube which is borderline defective?
Is it time to reprise the Carver challenge?

BTW, the Pass XA25 amp is capable of about a 100W peak output into a 6Ω load, as is typical of a Harbeth speaker.

Long-time listener's picture

"...I favor Leonard Bernstein's more poetically evocative interpretation with the New York Philharmonic..."

Subjectivity rules where musical preferences are concerned--yet I'd like to make the case that Bernstein's early New York Rite of Spring is not his best. And certainly not his most "poetically evocative"! That Rite, to my ears, is instead notable for its fierce energy and urgent forward momentum. For a classic Bernstein reading that equally succeeds in building tension and excitement when it should -- in the Dance of the Earth that concludes the first section -- while finding more poetry elsewhere, his Israel Philharmonic reading on DGG remains my favorite. The sound quality is also amazing, given its early digital provenance, being solid, weighty, colorful, and very spacious, yet virtually free digital glare. (Bernstein's 1972 London Symphony reading splits the difference, performance-wise, but is the most poorly recorded of the three.)

tonykaz's picture

Phew, non-extrapolating descriptives.

Mr. HR just keeps getting better and better.

I know a Scotch Whisky Judge who romanticilly describes the various and myriad flavor tones of Aged Laphroaig by splashing word-shadings to it's taste qualities. Our Mr.HR seems to be getting dam close to those phraisy UK image illustrators .

Well, this is a delightful read, it makes me pine to experience the same sense of thrill.

But, I'm still experiencing delight from my Sennheiser HD600 Headphones. ( does anyone have a loudspeaker/amp that can outperform them? )

Tony in Michigan

ps. I'll be going to North Carolina to meed those Cary people, they'll probably help me own something useful.

mrkaic's picture

HR is one of the reasons I did not renew my subscription to this magazine. If that is "getting better", then so be it.

tonykaz's picture

Is this some sort of mrkaic type Xmas Season comment example? : I cancelled and left but I'm still here making nasties !

Tony in Michigan

es347's picture

..bought these bad boys over 20 yrs ago and have no plans to “upgrade”..

Bogolu Haranath's picture

The new Meze Empyrean may do better ........ You can check the review by Headfonia, available on-line ..... The reviewer compared them with HD-650, among others :-) ..........

es347's picture

..thanks for the tip

Bogolu Haranath's picture

If you want to stay with Sennheiser, their latest design is HD-820 ......... It is a closed back design and is less expensive than Empyrean .......... It is a high impedance design, 300 Ohms :-) ...........

Bogolu Haranath's picture

HR could review Rogue Audio Pharaoh integrated amp for comparison, $3,500 ........ It is a hybrid tube/class-D transistor design ......... Rated 185 WPC/8 ohms and 350 WPC/4 Ohms :-) ...........

Bogolu Haranath's picture

May be HR could also review some of the Bob Carver tube amplifiers :-) ..........

..... or AD or JA (Heaven forbid) could review Carver higher powered tube amps :-) ..........

helomech's picture

The ST-100 is miles ahead of the Pharaoh (I've owned both), so I doubt Rogue will shoot themselves in the feet by submitting one for review.

helomech's picture

would be the Cary against the Rogue Cronus Magnum II - less than half the price of the SLI-100.

At least the CMII manages to output power near that of the manufacturer's claim. It also appears to have better quality transformers than the Cary.

Bogolu Haranath's picture

Yes, I agree ........ Cronus Magnum II would be better for a comparison review .......... CM II is not a hybrid design and is also rated 100 WPC :-) .............

ok's picture

..I’ve just got some beautifully distorted sound on my pc for 5971$ less.

Bogolu Haranath's picture

'Doubling' ........ double your pleasure with ............. :-) .........