Boulder 866 Stereo Integrated Amplifier Review
The journey continues. In pursuit of the finest in high-end audio stereo integrated amplifiers, last month I auditioned the Aavik I-580 from the Audio Group Denmark. The I-580 certainly deserved its position as the flagship integrated within the Aavik lineup, but it has just recently been upstaged by the new Aavik I-880. Stay tuned, as I will have an opportunity to review the I-880 early on in 2023. Next up is the esteemed Boulder 866 integrated which is the focus of this review. Following that, it seems that I will also have some time with the Vinnie Rossi Brama integrated and the D'Agostino Progression integrated. Hang in there with me folks! Without question, 2023 is going to be a fantastic year for integrated amplifiers!
The Boulder 866 Integrated Amplifier
Every new visitor to my listening room immediately commented on the 866 and almost nothing else. This says a bunch, as I also have the elegant Sonus Faber Stradivarius speakers in the room along with other audio eye candy from REL, VAC, and Pass Labs. Every comment on the 866 aesthetics was positive if not a rave. Even the most discriminating could not help but admire. Bravo Boulder!
One note on the USB-A inputs. They only support USB storage devices and external drives. They cannot support USB output or playback from a computer. The stated opinion by Boulder is that Ethernet or network playback is preferred to USB playback. When considering sound quality, their position is that Ethernet has advantages in terms of both speed and the ease or ability to implement high resolution when compared to USB.
Again, I found the industrial design and aesthetics of the 866 chassis to be quite compelling. The satin finish, the 10 to 15-degree angle of the front panel, the large full-color display, and its most striking feature, the staggered heatsink fins, are like nothing else that I have seen in any other component. In my humble opinion, the end result is virtually one beautiful piece of art. I was also intrigued to see that Boulder has implemented this "look" in the new Boulder 812 DAC Preamplifier shown below.
Power for the unit is engaged by on/off switches on the front panel (labeled with a Stand-By symbol) and the rear panel (labeled Power). The intent is to leave the rear switch on and use the front switch for daily On and Off functionality. This allows for some low-power components to remain on continuously or in standby mode. Obviously, this can provide savings on your monthly electric bill, and can also avoid excessive warm-up periods to achieve ultimate sound quality.
The front panel includes a fairly large full-color touch display (6.1" x 3.3") that is easily visible from most sitting positions. All settings and functions for the unit are accessible from this display and also via the iOS Boulder App. I found the menus quite easy to maneuver and very logical when selecting preferred options from either the display or the App.
The 866 display can also provide album art from streamed music and custom icons for both analog and digital inputs. This includes your own graphics or pictures for your specific source components (very cool). There are four switches on the panel next to the display for volume up, volume down, mute, and standby.
Key differentiators and design choices for the amplifier include the unique implementation of the gain stages, the use of extremely low noise attenuators, and a distinctive if not transcendent ground topology. Pots and variable resisters are not used to avoid long-term noise and reliability issues. This all supports an extremely consistent and reliable sound quality at any volume level — there is no sweet spot like other designs. Crank it up or listen on the down low. You will be very satisfied at any setting.
The 866 DAC is said to be an extension of the Boulder 2120 DAC design and utilizes a single differential DAC chip per channel. Digital sources are connected to the 866 DAC via a uniquely integrated Raspberry Pi and are upsampled to 352.8kHz. The 866 DAC also utilizes an ASRC (asynchronous sample-rate converter) and its own internal master clock for re-clocking all digital signals.
As a certified Roon End Point, all the advantages of Roon and supported services like Tidal and Qobuz make the 866 a highly desirable solution for those interested in streaming as a key music source. For this review, I utilized my Aurender N-10 Music Server and an AES/EBU interface for all digital playback. This included Qobuz, Tidal, and my library of high-resolution music files. It worked flawlessly.
A remote control is not included with the 866, but standard off-the-shelf USB remotes can be implemented. Most folks will use the Boulder App and/or Roon for settings and key functions like volume control. I almost always reached for my iPad whenever adjusting the volume or selecting an input. And of course, these same settings and functions can be accessed at the front panel.
Working from the bottom up, the 866 had a muscularity in the lower frequencies with plenty of blunt power and visceral impact. When compared to my tube VAC Signature preamp and Class A Pass Labs XA-100.5 monoblocks, there was a distinct improvement in low-end weight and agility. The 866 provided a vice-like grip on my Strads — never any bloat or boom. The extra power and drive really pushed my Strads to deliver everything that they had to offer in terms of bass performance.
I was somewhat surprised by the purity and harmonic richness of the mids. Without question, this was the finest midrange from a Class A/B amplifier that I have experienced in my listening room. That includes separates and integrated amplifiers. Male and female vocalists were wonderfully fleshed out and seductive. Reed instruments growled with a woodiness and harmonic purity that had me reaching for all my favorite jazz quartets.
Highs were somewhat relaxed and laid back compared to other benchmarks. There was still plenty of air and openness, just more of a delicate shimmer and sweetness. Soundstage and imaging were clearly delineated and three-dimensional. Micro and macro dynamics were as good as any integrated amplifier that I have reviewed. Whatever the recording called for, the 866 delivered. This in itself is a huge accomplishment where other components can often fail.
The Boulder 866 DAC Versus The dCS Bartok DAC
Again, caveat emptor! This is not a fair apples-to-apples comparison when considering both hardware and firmware costs for both DACs. As an integrated solution via an integrated amplifier, the 866 DAC is supported by a completely different build philosophy and execution. However, this does give you a sense of pause and a sense of value.
In terms of performance, the 866 had a familiar level of definition and speed as the original Bartok. There was also a fundamentally correct presentation of proper timbre and tone that was readily present in both. The lack of digital edge and grain is also a major strength of both components.
The new Bartok 2.0, however, with its improved mapping algorithms and upsampling functionality, has taken performance to a whole new level. More nuance. More power.More transparency. Let me tell you, original Bartok owners are ecstatic over the upgrade. The Internet is flowing with rave reviews. But still, the Boulder 866 DAC has to be considered a real winner for the money.
Tracey Chapman, Crossroads (Tidal MQA
Ben Webster, Gentle Ben (WAV 24-bit/192kHz)
Voice: (303) 449-8220