Burson Audio Soloist Preamplifier/Headphone Amplifier (Playback 60)

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Burson Audio Soloist
Burson Audio Soloist Preamplifier/Headphone Amplifier (Playback 60)

Long-term Playback readers know that we are great admirers of the Australian-made Burson Audio HA-160 headphone amplifier and AB-160 audio buffer. Both products make sense to us, and the HA-160 in particular offers a ton of value for the money. But now, Burson has created a new flagship headphone amplifier called the Soloist ($999), which can also serve ably as a three-input stereo preamplifier. Once you consider how good the HA-160 is you might rightly expect it to be a tough act to follow, and it is. Even so, Burson claims the Soloist sounds even better, offers considerably more flexibility, and—dare we say it—is potentially an even better value. Can the Soloist back up these claims? That’s precisely what this review aims to find out.

FEATURES/TECHNICAL HIGHLIGHTS

  • Improved chassis vis-à-vis the original Burson HA-160. We have long admired the construction of Burson chassis, which feature sturdy, non-resonant side panels carved from (very) thick sheets of aluminum of slightly different thicknesses, to help fight unwanted resonance. What is more, Burson chassis have been designed to serve as “unified heat sinks” for the pure class A audio circuits found within. These characteristics carry forward into the Soloist, but with two improvements:
    • Improved panel joining techniques are said to require fewer parts while providing “higher structural integrity” and “higher precision” of fit, which is saying something when you consider that Burson amps have always been built like Aussie interpretations of Swiss bank vaults.
    • Burson says exterior panel surfaces are now treated to extra polishing processes, so that all surfaces—including the base plate—“can be described as beautiful.” And indeed, they are beautiful.
  • New “symmetrical transistor” amplifier input stage using FET (Field Effect Transistor) devices.
    • In the process of creating the Soloist, Burson invested in a 6-month development effort to create an even better sounding input stage than the one found in the original HA-160, where the initial concept had been to design a “symmetrical-transistor” input stage based on bi-polar transistors.
    • The resulting bi-polar device-powered input stage measured very well and sounded good in terms of dynamics and detail, but it did not fully meet Burson’s sonic expectations—especially not in the all-important midrange.
    • Unwilling to settle for compromises, Burson went “back to the drawing board” for another 12-month-long development effort to create an all-new symmetrical-transistor input stage based on FET devices. The new input stage, which is at the heart of the Soloist, offers what Burson terms a “lively and coherent sound that is a combination of all the strengths of FET and bi-polar transistors.”
  • “Less-is-More” design approach:
    • Burson has long avoided using IC-type (integrated circuit) opamps in its products, arguing that even the best IC-type devices sound inferior to discrete transistor designs.  The firm also passionately believes that simpler audio circuits generally sound better than complex ones.
    • For the Soloist, one key goal was to “remove as many components from the signal path as possible while still maintaining ideal operational levels.” The Soloist input stage uses just 21 components in the audio signal path as compared to 32 components for the HA-160 input stage or 53 components for a typical NE5534 IC opamp-based input stage. Burson describes the benefits of its newly simplified circuit with this slogan: “Less Blockage, More Music.”
  • The Soloist provides considerably higher power output (4W @ 16 Ohms) than the HA-160 did (250mW).
  • The Soloist incorporates a very low-noise power supply.
  • The Soloist incorporates what Burson terms a “high resolution volume control”; that is, a stepped attenuator-type volume control based on precision-matched, high-quality/low-noise resistors. Burson builds and assembles this volume control in-house.
  • More usable features: The original Burson HA-160 provided a single stereo input and two output jacks, each optimized for a different impedance range of headphone. The Soloist goes much further to provide:
    • Three stereo analog inputs.
    • One variable-level stereo analog output, which gives the Soloist preamp capabilities should owners wish to use the Soloist to drive power amplifiers and thus full-size hi-fi systems.
    • Three switch-selectable levels of gain, to adapt the Soloist for use with headphones of varying impedance/sensitivity levels.
    • The multi-level gain switches also affect the Soloist’s gain levels as a preamplifier.

SONIC CHARACTER

Other equipment used in this review

Headphones: Audeze LCD-3, HiFiMAN HE-500 and HE-6, Sennheiser HD 800, and Shure SRH 1440 and SRH 1840.

Earphones: Ultimate Ears IERM and PRM

Source components: Oppo BDP-95 universal/Blu-ray player, NuForce-edition Oppo BDP-83 Special Edition universal/Blu-ray player.

Power amplifier: Anthem Statement P5 (left and right channels only)

Speakers: PSB Imagine T2 floorstanding speakers.

The Soloist as headphone amplifier

More so than was the case with the HA-160 amplifier, the Soloist seemed to need a fair amount of run-in and warm-up time in order to reveal its full sonic potential. Straight from the box, the sound is not unpleasant and showed flashes of real brilliance, but tended at first to be a bit warm and opaque. As playing time accumulated, though, the Soloist opened up and became progressively more transparent sounding in a most convincing way.

Heard at its best, the Soloist offers a lively and energetic sound, with excellent control over both macro- and micro-dynamics, plus—thanks to the Soloist’s three-level gain switches—the ability to dial-in power and gain-on-demand sufficient for even the most difficult to drive headphones (the Soloist comfortable drives the HiFiMAN HE-6 without any apparent stress). I found that with most headphones, the best approach was to set volumes at moderate levels and to toggle through the Soloist’s three gain settings until I found the best combination of adequate power and low noise for the headphone at hand. (Your ears will tell you right away when you’ve found the best gain setting for a given headphone, though it’s easy to toggle through settings if you wish to experiment further). One upshot of having a range of three available master gain levels is that the Soloist can work equally well with very sensitive headphones on through to ‘phones that are extremely low in sensitivity and hard to drive. The Soloist is more powerful than, but also more flexible than, the HA-160—two meaningful differentiators prospective buyers may want to consider.

Next, the Soloist sounds highly transparent and detailed, even more so than the already very good HA-160. I noticed these differences all across the audio spectrum, but especially in the very heart of the midrange. I would liken the difference between the Soloist and other good headphone amps near its price to the difference between looking at a beautifully shaped three-dimensional sculptural object vs. looking at a fine, but ultimately flat, two-dimensional photograph of the same object. Both have gorgeous lines, textures, shadows, details, and so forth, but at the end of the day the sculptural object conveys a believable sense of depth, contours, and solidity that even the best of photographs cannot fully match.

So it is with the Burson Soloist. Other fine headphone amps (e.g., the very good though somewhat more expensive Audio Electronics/Cary Audio Nighthawk) may initially seem to provide more crisply drawn leading edges of notes or greater definition, but the longer you listen to the Soloist more aware you become of the almost sculptural shadings and inner details the Australian amp provides, Moreover, it does a great job with the complete envelope of each note—not just with leading edges but with the whole note in its entirety, bringing to each element a great combination of delicacy, finesse, and power.  In the end, the superior three-dimensionality, solidity, and whole- -note completeness of the Soloist are what set it apart from, and in my mind place it above, its like-priced competitors.

Voicing: At first the Soloist give the impression of providing tonal balance tipped slightly to the warm side of neutral, owing both to the Soloist’s ample bass output and unexaggerated highs. After a closer listen, I feel the first impression is illusory and that the Soloist is actually quite neutral in its presentation. It’s just that it has robust bass output (and especially mid-bass output), where many other headphone amps tend to sound a little thin, and it also steadfastly refuses to use upturned highs or exaggerated treble transients to create a sense of heightened detail. Once you get acclimated to the Burson’s sound, some competing amps can seem a bit brittle and anemic-sounding by comparison.

The Soloist as stereo preamplifier

The Soloist’s virtues as a preamp run parallel to its strengths as a headphone amplifier, but with this difference: the superiority of the Soloist’s three-dimensionality and soundstaging are, if anything, even more obvious in the context of a full-size hi-fi system. When I tried the Soloist as a preamp, I found that it produced broad, deep soundstages with the greatest of ease and with virtually no tendency for the sound to “cling” to the front baffle surfaces of the speakers. What is more, the placement of instruments within soundstages was remarkably precise and well focused. Overall, the Soloist yielded up a sound that was both more natural and more refined and much more three-dimensional than I’ve heard from other preamps in its price class. While a few products designed as preamps first and as headphone amps second may have more features (as in more inputs and outputs, recording monitor loops, and remote controls), the fact is that the Soloist effortlessly stands tall in their midst in terms of pure sound quality, which is precisely what Burson intended.

Can the Soloist top today’s better multi-thousand dollar stereo preamps? I would say it cannot, but that the performance gap is smaller than you would expect and certainly does not draw attention to its self. The primary difference you might hear is that some of today’s better upscale preamps do offer somewhat higher levels of transparency and resolution, though for a very substantial jump in price. Even so, the Burson’s sheer naturalism and spectacular 3D imaging make it rewarding to hear, even in contexts where it may be the least expensive component in the system.

Are there caveats involved in using the Soloist as a preamp? I can think of two small ones. First, the Soloist has no remote control—a feature many listeners have come to desire and expect. I suspect this design choice involved the fact that it is both complicated and expensive to build remote control systems that do not add noise or distortion. Also, remotes tend to fly in the face of Burson’s “less is more” design philosophy. In a forced choice, I would rather have the sound of the Soloist as is than to have a less good-sounding preamp, just for the sake of a getting a remote.

Second, note that the Soloist’s preamp outputs are disabled whenever you plug in headphones, which could be a benefit or a drawback depending on your point of view. The present arrangement invites you to do headphone listening without disturbing others, of course, but precludes the possibility of listening through ‘phones while having your main hi-fi system in play at the same time.

MUSICAL EXAMPLES

The Soloist comes alive on well-made recordings, giving terrific results whether driving headphones or full-size hi-fi systems. A good demonstration vehicle for the Burson’s capabilities would be Paquito D’Rivera’s The Jazz Chamber Trio [Chesky], featuring D’Rivera on clarinet and alto sax, Mark Summer on cello, and Alon Yavnai on piano. What surprised me, and I think would surprise most listeners, was first the Burson’s natural warmth and tonal purity in capturing the voices of each of the instruments, but just as importantly its ability to retrieve small, very low-level imaging cues (echoes, reverberations, etc.) that helped convey a sense of place (the recording was made at he Foundation for Iberian Music in The Graduate Center at the City University of New York). These low-level cues were highly audible through headphones, but downright spectacular when the Soloist was used to power a good, full-range hi-fi system. There, the sense of the trio performing in a real acoustic space (not a studio) was simply uncanny.

Under “SONIC CHARACTER”, above, I spoke of the Soloist’s ability to be true to the whole envelope of the note, and not just to the leading edges of notes. To hear what I mean by this comment, try listening to the well-recorded “Brand New ’64 Dodge” from Greg Brown’s The Poet Game [Red House], where subtle vocal inflections and delicate instrumental comment are used to speak volumes (the song is an indirect commentary on the relative innocence of life in the US in the time just prior to the assassination of President John Kennedy). If you play this track through good competing headphone amps, such as the $1195 Audio Electronics/Cary Audio Nighthawk, you’ll be treated to a performance rendered with impressive and almost crystalline purity. By comparison, the Soloist might initially seem less overtly well-defined, but by the time the track ends there can be no doubt that it has taken you much deeper inside the recording, letting you feel, hear, and more fully appreciate the arc and shape of all the notes. If, after careful comparison sessions, you ask yourself, “which headphone amp left me with a better understanding of, and a clearer emotional connection with, the music?” my bet is that your answer will be that the Soloist has consistently shown you more of what’s there, and why.

Is the Soloist all about audiophile-grade finesse, or can it get down and boogie? It most certainly can, as you’ll discover if you put on an evocative, high-powered R&B track such as “She’s So Scandalous” from Black Joe Lewis & The Honeybears' Scandalous [Lost Horizon]. When properly reproduced, this track has the cool ability to present some sonic elements with deliberate touches of distortion, while offering other with almost casual, pristine clarity. The track opens with a very powerful yet undistorted kick drum figure that is supported be catchy snare drum and high-hat pattern, with a delicious, deceptively simple, and decidedly rough textured and slightly distorted lead guitar theme setting the mood. 

As the song unfolds, Lewis’ vocals are potent and at times verge on microphone saturation, flirting with disaster, but never quite going over the edge. Later, the Honeybears’ terrific horn section joins in and sounds amazingly clean, crisp, pure and rhythmically synced with the rest of the band. But perhaps the coolest part of all is hearing the big, almost impossibly fat-sounding punch of Bill Stevenson’s electric bass guitar as it joins forces with Matthew Strmiska’s drums to bodily propel the song forward with a funky, down’n’dirty lope. I had the joy of listening to this track for the first time through a pair of Sennheiser HD 800—‘phones that have a reputation for being amazingly accurate sounding, yet perhaps also for sounding a little analytical and “uptight.” But when you leave the driving to the Soloist, the flagship Sennheisers lose most of that clinical, overly-tightly-wound quality and just open up and get funky, with a really impressive combination of dynamic energy and abandon coupled with the HD 800’s signature control and clarity. Part of the reason to admire the Soloist is that it has a knack for bringing latent excellence (and musical fluidity) in many headphones out in the open where you can enjoy it. 

CONCLUSION:

Consider this preamp/headphone amp if:

  • You appreciated the original Burson HA-160 but wanted something more; the Soloist gives you just that with superior clarity and subtlety, more power, and greater versatility.
  • You believe in Burson’s “less is more” design philosophy; as it turns out in this case, using fewer components in the audio signal path really does make for a big jump in transparency and openness.
  • You want an amp with plenty of power for hard-to-drive ‘phones.
  • You like the idea of a headphone amp that also works as a preamp to serve as the front end of your full-size hi-fi rig.

Look elsewhere if:

  • You wanted a headphone amp with balanced inputs and/or outputs.
  • You like the concept of a preamp/headphone amp, but want one that comes with a remote control.
  • You want a headphone amp that offers more overt definition or apparent clarity; the Soloist provides both of these qualities, but its most obvious strengths are midrange subtlety and three-dimensionality.

Ratings (relative to comparably-priced amps):

  • Tonal Balance: 9.5
  • Clarity: 9.5 – 10 (midrange clarity is exceptional)
  • Dynamics: 10
  • Input/Output Flexibility: 10 (switch-selectable master gain settings enable the Soloist to work with a very broad range of headphones; preamp features are cool, too)
  • Value: 10

BOTTOM LINE

The Soloist takes substantial steps forward relative to the already very good Burson Audio HA-160, offering better and more refined sound, greater power, superior versatility, and exceptional build-quality, all at the more-than-fair price of $960. For what it is and does, the Soloist is a bargain, and a versatile one at that.

SPECS & PRICING

Burson Audio Soloist Preamp/Headphone Amp
Accessories: Power cable, RCA stereo input cable, user manual.
Inputs: Three single-ended stereo analog inputs (via RCA jacks).
Outputs: One variable-level stereo analog preamp output (via RCA jacks), one ¼-inch headphone jack.
Frequency Response: 0 – 50kHz, ± 1 dB
THD: < 0.03% @ 30 Ohms at 1W output
Power Output: 4W @ 160 Ohms
Dimensions (H x W x D):3.15” x7.09” x 9.84”
Weight: 9.92 lbs.
Warranty: 2 year, parts and labor (requires Burson product registration)
Price: $999

Manufacturer Information
Burson Audio
www.bursonaudio.com

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