Boulder 866 integrated amplifier

What's the first thing that comes to mind when you hear the word "boulder"? I think of a rugged, mountainous landscape with jagged snow-capped peaks. I see images of the last time I drove up from sunny Boulder, Colorado, to Rocky Mountain National Park and discovered so much snow coming down that if we had dared walk too far in, our trail would have been covered with snow and we'd never have been able to find our way out. But how magical it was!

My first visit to the area was in late July 1972. I was fleeing New York City for the Bay Area in an old car that burned oil. The park provided welcome relief from the long, monotonous drive. The Summer of Love was long passed, but when we stopped high in the park and ran through wildflower-covered mountainsides, I felt like the flower child I never was. Today I view that escapade with regret—in our innocence, we were unaware that our carefree frolic was doing lasting damage to a fragile landscape—but I'll never forget the joy that flower-covered mountainside brought.

I want my audio components to grant me experiences as varied, risky, and ecstatic as those I've had around Boulder. I want the high end to transport me to Strauss's climactic peaks and into the heart of Schubert's winter despair. When I listen, I want to feel as cool and sophisticated as Patricia Barber and as joyous as a choirboy singing of sleigh rides through the snow.

That's a tall order. Can Boulder Amplifiers' new 866 integrated amplifier ($13,450, or $14,950 with optional upsampling Roon-ready streaming DAC)—which co-designer Jameson Ludlam told me was "a more accessible product that provides the features we think many people are looking for with the performance they have come to expect from Boulder"—reach the summit?

The terrain
The Boulder 866 integrated amplifier's chassis somewhat resembles an accordion, with an angled front panel and irregularly shaped, oddly angled, smooth-edged heatsink fins. Dominating the view is a large color display that's easily read from 12' away. Four large buttons (volume up and down, mute, standby/on) are lined up on the right under the engraved nameplate. The 866 looks unique, sophisticated, and accessible.


Rear connections include three pairs of XLR analog inputs and two pairs of Boulder's signature, easy-to-tighten binding posts. The 866 comes in two versions: "all-analog" and "analog+digital." The "analog+digital" version adds AES/EBU, Ethernet (RJ-45), and TosLink digital inputs and four USB-A receptacles, the kind of USB used to connect a USB storage device (footnote 1); you cannot connect a computer by USB. "It is our opinion that Ethernet or network playback is preferred to USB playback. Ethernet is incredibly fast. It is difficult to get full high resolution through USB, and Ethernet doesn't have those kinds of problems [because it] is not distance-limited the way USB is."

What's inside? It's a secret—not. "We're kind of a bit of a hush-hush company," Ludlam explained during our call. "We don't like telling people too much about how we do things." He then proceeded to say quite a bit.

"What matters on the technical front is what choices you make as a designer and what compromises you carefully consider."

Ludlam worked with Boulder founder, company head, and analog specialist Jeff Nelson, laying out the circuit boards and overseeing how the product was assembled. "I didn't design the DAC software, but I did design how the data enters and exits the DAC and how we go from digital to analog," Ludlam told me.


"This is a drastically different design than our old integrated. The 866 has digital inputs, a completely different interface, and performs at another level. Some of the biggest circuit-design differences are in the volume attenuators, how the gain stages work, and grounding topology. In designing the flagship 3050 mono amplifier, we used a grounding technique that exists in the RF world and that, as far as we know, no one in the audio world is doing. But it's made every product we've produced since the 3050 better.

"The biggest contributor to the Boulder sound is that we treat analog like analog. ... Our biggest amps have a differential output, which means that they drive both the plus and minus output of the speaker terminal. You might think of it as a kind of bridged amp that drives the speaker differentially. [Each amplifier in] the 800 series, by contrast, is like a regular amp where the minus terminal is zero volts all the time. Besides that, there's just more stuff in our bigger and more powerful amps. With the 866, we did try to simplify certain aspects. But the overall design mentality is the same. Our attenuator has very, very little noise. We don't use pots or variable resistors because they wear out and start to crackle. You get the same sound quality anywhere on the volume control—it just gets louder as you turn it up. There's no sweet spot in the volume control.

"In our top-level products, we hand match and calibrate components to extremely precise percentages, selecting a few parts out of thousands," Ludlam said. "Whatever doesn't make the cut can still be used in less critical circuits or the next levels down." There's less meticulous parts-matching in the 866, another cost-cutting measure.

From Roon, I learned that the 866 upsamples PCM files to 352.8kHz. Ludlam wouldn't say which DAC chip the 866 uses, but he did say it's a single differential DAC chip per channel and that it's not one that's commonly used in high-end audio. "It requires a lot more external support circuitry than the typical DAC chips that other audio companies usually employ.

"We have never been discouraged by complexity in circuit design, so we actually prefer to do as many of the circuits ourselves as possible rather than relying on more of an 'off the shelf' DAC topology. We use the DAC chip in an undocumented mode. As far as we know, no one else uses it like this. Rather than letting the DAC do the computing, we do our own math in DSP and then feed that data to the DAC chip. We always send the same kind of data to the DAC regardless of what file type you're using. That's the beauty of DSP. ... If we found a better DAC chip, we would use it, but we haven't found a better one that also supports playback of DSD 64 and 128."

I've spoken with many a company owner, designer, and rep over the years, but few have provided such an honest assessment of a product's strengths and limitations.

"Obviously, bigger amps give you more control of the woofer and a greater sense of scale. A speaker is really a motor. An amplifier puts voltage across the motor, the motor pushes a cone, and that cone pushes air at you. A bigger amp pushes the speaker the way it wants to; a smaller amp sometimes gets pushed around by the speaker. We have very high damping factors on all our products—we have lots and lots and lots of control—but you just get more with more.

"The big amps create a space, a separation between the background and what you're listening to. They move things more precisely, and everything stands out proud from the background. More power gets you a better sound if you know how to control it.

"Ultimately, what I'd say to people is that you need to listen to this integrated and see if it brings you happiness. That's the whole point: to experience happiness. I could wax on and on about technical matters, but just listen to it. Of course, the bigger stuff is better, but this still sounds really great and is reachable by far more music lovers. It is a fantastic-sounding amplifier."

Following Ludlam's advice, I'll be the judge, as I hope you will, too.


Preparing for the journey
To cut costs, Boulder put the 866's owner's manual online, including only an illustrated Quick Start Guide in the box. The documentation is thorough, with just one oversight: There's no mention of the fact that the diminutive "remote receiver" you must plug into one of the unit's USB ports to enable communication with the remote comes stashed in the remote's empty battery compartment (footnote 2). Presumably, Boulder will amend its literature to address this—and to offer pointers on how to open said battery compartment.

Although a digitally equipped 866 has its own wireless network, which you can use for file playback when a wired connection is not possible, Ludlam and sales coordinator Logan Rosencrans both urged me to hard-wire the 866 to my own network. Hence, I moved my Wireworld Ethernet cable over to the 866 and switched audio settings in Roon.

When asked whether a power conditioner should be used, some amplifier manufacturers urge caution. Boulder is one of a handful of companies to issue an unqualified "no." I've almost always found, though, that my AudioQuest Niagara 5000 improves bass control and impact, removes noise, and produces a more transparent and lifelike representation of music. I went back and forth between the wall and one of the Niagara 5000's high-current receptacles, comparing sound. My typical experience was confirmed one more time: I noted a bit more texture and detail on voice and instruments with the 5000, more saturated colors, a better-defined sense of space, and better bass. I mentioned this to Ludlam.

"I'm not here to dictate," he answered. "We say 'no power conditioners' because we tire of very long conversations where we argue about the merits of one over the other. It's much easier to say, 'No power conditioners.' But if it works, it works. My biggest concern is that there are some that have ground lifts and actually have a driven ground. Legally, those are not UL certified." (footnote 3)

Footnote 1: USB sticks can be used by themselves, but hard drives require more power than the USB port can provide and so must be self-powered.

Footnote 2: I thought I'd lost it, which made me none too happy.

Footnote 3: When questioned about this, AQ power conditioner designer Garth Powell wrote, "All grounding of the Niagara 5000's high-current outlets (for power amplifiers) is chassis star-grounded and NRTL code–compliant. Our international units are CE compliant as well. ... I take electrical safety very seriously."

Boulder Amplifiers, Inc.
255 S. Taylor Ave.
Louisville, CO 80027
(303) 495-2260 x116

georgehifi's picture

How nice it is to see extended frequency response and a pure untouched 10k square wave like this without the need of an Audio Precision auxiliary AUX-0025 passive low-pass filter to hide/mask the switching noise oscillations all over it. Like Class-D needs to make it look not even half as good as this, and with out the AP filter!! buzz saw comes to mind, but sadly that not shown anymore, as it's too visually bad for business.

Cheers George

RH's picture

- - - "I appreciate warm sound, but acoustic music does not sound overtly "warm" in the various halls I frequent. "

I'm not sure how exactly to interpret that part of the review. But from my perspective as someone obsessed with the differences between live and reproduced sound, one of the distinguishing characteristics to me of live acoustic sources is "warmth." The average sax, trumpet, trombone, even acoustic guitar, sounds so much bigger than on most audiophile playback systems I've heard. Most reproduction to me has a reductive, hardening effect on most acoustic sources. "Warmth" in terms of fullness of "body" and richness of harmonics is just what I hear in acoustic music vs reproduced, virtually wherever I am situated to the music, or in whatever hall I listen.

Of course, since essentially all reproduction is compromised in regards to reproducing true realism (especially if we are talking about symphonies!), it's a pick-your-compromise and we tend to zero in on the aspect of sound that strikes us as most consonant with reality. Some may zero in on the transient precision and dynamic presence of, say, some horn systems, others may find the more relaxed richness of another speaker gets at what they hear in real music. I tend toward (certain) tube amplification insofar as I hear a bit more of that roundness, body and relaxed warmth I pick up on when hearing live sources. YMMV of course...

brenro's picture

Save $6000 and buy a Krell K-300i.

Ortofan's picture

... Rotel Michi X3.

tonykaz's picture

Nice work, Mr.Jason!

The Boulder is probably a nice piece of gear but I'd still insist on a Round Volume knob, the bigger the better. I'd even like the power switch to be mounted behind the volume knob in an Old School way of things with the Volume knob acting as the OnOff control like an old Car Radio.

Does this Amp have a sloping Front Panel like the Pictures seem to show?

Anyway, nice work Jason,

Tony in Venice Florida

Anton's picture

It can compress to as little as four inches deep or expand to as much as 28 inches.

Front face angle is as you desire.

tonykaz's picture

Brilliant observation!

I wonder if they built it that way to save on the Dimensional Weight Shipping Formulations?

I have a bit of Vintage gear that mostly remains rather tiny but enlarges when the occasion arrises! I never show it to anyone, ( mostly out of embarrassment and because it ain't pretty ).

Tony in Venice Florida

Kal Rubinson's picture

It can compress to as little as four inches deep or expand to as much as 28 inches.

Does it move from Class A/B to pure Class A as it expands? :-)

Jason Victor Serinus's picture

a lot of us would be in a class above.

nomaslarge's picture

This does feel a little like one of those "damned with faint praise" reviews and the comparison to the k-300i is vague and leads one to believe that to the reviewer's ears it's really a tossup based on what you like (which obviously for most of us would lead to the conclusion of "I'll take the one that is $6k cheaper"). I know that JVS loved the k-300i and it was been very well reviewed elsewhere - I admit I've never heard it. But the K-300i is often compared to a unit I owned for a while - the Naim Uniti Nova. I thought the Nova was impressive and enjoyed it more than I thought I would given that when I got it I was coming from a pricey VAC tube rig. I briefly considered trying the K-300i while I had the Nova and spoke to a few people with experience of both units who felt that it would be a sideways move unless I really needed the extra power of the Krell. I then went to a Pass Int25 which to my ears was just in a different class than the Nova - I won't bore you with the details, I'll just leave it at the fact that for me this wasn't even a close comparison in terms of what these amps were capable of. And now recently I got a Boulder 866, which I find to be in an altogether different class than the Int25, by at least as significant a margin as I found the Pass to be superior to the Naim. The Boulder feels to me like it competes with some of the high-dollar separates that I've owned in the past. Because of the surprisingly high performance of the DAC, it almost seems like a bargain at its price. Of course, the commutative property doesn't always hold in audio... but for these reasons I am skeptical that the 866 and the K-300i are on a level playing field with only one's preferences and about $6k sticker price separating them.

Salva69's picture

Jason Victor Serinus could be a good music reviewer but as a gear reviewer, I feel sorry to say that he is the most boring I've ever read in the pages of Stereophile.

nomaslarge's picture

I find JVS to be an excellent writer but I don't get the sense the 866 inspired him very much which is... you know... the way it is sometimes with gear. Who knows why it is that some pieces excite us and others don't. The 866 has excited me quite a bit which is why I left my earlier comment.

tonykaz's picture

Music is a delightful life companion, sharing that experience is a nice gift to us all.

Thank you,

Tony in Venice Florida