• HD Opamps: As a signature feature, the HA-160 (along with many other Burson products) uses class A circuitry and what the firm terms HD Opamp modules that are based on hand-picked discrete devices—not on garden-variety integrated circuit chips. Burson adamantly maintains that IC-type opamps are incapable of genuinely high-level sonic performance, and thus offers an alternative. Burson’s HD Opamps feature precision-matched transistors, 1% tolerance resistors, ultra high-quality capacitors, and so on. Many components within the HD Opamp are chosen through an expensive and time-consuming “burn-in-then-match” selection process, which ensures that incredibly tight tolerances are maintained. Burson even assembles its modules using special lead-free solder and a temperature-controlled soldering process, rather than using the sort of generic wave solder bath that is commonly used in construction of mass market electronics.
• Low noise power supply: As with its opamps, Burson eschews IC-based power supply regulators for its power supplies, instead choosing to use discrete devices to create a “sophisticated noise filter and voltage stabilization system."
• High-precision volume control: Rather than use a conventional potentiometer for the HA-160’s volume control, Burson builds its own 24-position stepped attenuator that, again, uses precision-matched resistors. The argument is that a well-made stepped attenuator can do a superior job of preserving sonic details from very low-level audio signals. No remote control is provided, since Burson claims that remote controls almost invariably introduce unwanted noise that muddles the audio signal, at least to some extent.
• Resonance Free Aluminum (RFA) Enclosure: The HA-160 chassis is made up of panels precision-machined from slabs of aluminum, each designed to have a slightly different thickness and thus a different resonant “signature.” The case not only serves to resist mechanically induced noise, but also makes a great heat sink, thus allowing Burson to run higher idle currents in its amplifier modules. Higher idle currents, in turn, are said to help yield “lower distortion, higher output, and better overall dynamics.”
For this review we did much of our listening through four very revealing full-size headphones: the Audeze LCD-2, the HiFiMAN HE-6 and HE-5LE, and the Shure SRH840. I also used several very high-performance custom-fit in-ear monitors, including the Westone ES5 and Ultimate Ears In-Ear Reference Monitors.
Source components included: a Musical Fidelity kW SACD player, an iPod Classic with digital outputs fed through an HRT iStreamer DAC, and an analog system consisting of an Nottingham Analogue System Ace-Space 294 turntable/Ace 294 tonearm fitted with a variety of Shelter moving-coil phono cartridges (the 901 MkII, 9000, and Harmony MC), with cartridge signals fed through a Fosgate Signature tube-type phono stage.
I auditioned the Burson Audio HA-160 both with and without its optional, outboard Burson Audio AB-160 RCA buffer stage*.
* Note: The AB-160 RCA will be the subject of its own Playback mini-review that we hope to publish in the next few weeks.
The Burson serves up a dead neutral, full-bodied, and highly detailed sound that is immediately engaging—deeply so. The unit needs a bit of warm up (about a half hour or so) to sound its best, and in an absolute sense sounds subtly smoother with more fully saturated tonal color after it has been allowed to run-in for a week or more. In fact, I’d follow Burson’s suggestion that you leave the HA-160 powered up all the time, so that it’s always ready to go. But now, let’s take a moment for a closer look at the sonic qualities I’ve sketched out above.
Neutrality: It’s tempting and in many cases easy to describe components in terms of minor ways in which their response curves are skewed, even if only very slightly, away from strict neutrality. But this is not the case with the Burson. The Burson sounds about as perfectly balanced from top to bottom as any audio component I can think of and, significantly, it maintains this balance regardless of the load being driven. Burson flatly rejects the notion that you have to match headphone amps to specific headphone loads, arguing that a well-designed amp can and should be able to handle any reasonable load. In practice, this is one of those things easier said than done, but the HA-160 not only talks the talk, but also walks the walk.