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This is the 14th in a series of reviews dedicated to the concept of 32Ohm Audio as embodied by the store of that name in downtown Portland/Oregon and described here - Ed.
Reviewer: Srajan Ebaen
Financial Interests: click here
Source: Raysonic CD-228, April Music Stello CDT100 /DA100 Signature [on loan]
Preamp/Integrated: KingRex HeadQuarters [on loan], Red Wine Audio Isabellina HPA [on review]
Headphones: Sennheiser HD800 w. ALO Audio wiring, AudioTechnica ATH-W5000, Grado PS-1000, AKG K702 with ALO Audio wiring
Cables: ASI Liveline
Powerline conditioning: Walker Audio Velocitor S
Review Component Direct Price: $699 including postage to the US, €499 including postage to EU

The DIY blokes of Burson Audio have built their little hifi emporium in Melbourne of Oz on the notion that ICs stink and that discrete is the magic bullet. Ouch. I spent good cash years ago on power amps with integrated chip outputs—Peter Daniel's gain clones—and later a lot more dosh on the brilliant Esoteric C03 preamp which again runs ICs for gain devices. You might appreciate how I'm unconvinced that a categorical character assassination of these many-legged little fellas is really on.


Restraint seems particularly apt for the milli voltages at which headphone amplifiers put out. Many a primo can amp runs on ICs after all. Think Ray Samuels or ALO Audio Rx for two easy examples. For Burson's anti propaganda that "the only excuse for ICs are cost savings", their own website is the best resource of course. It also explains the company's rich history, roots in broadcasting, focus on cost-effectiveness and decades-long interaction with domestic DIY circles.

Every savvy audio firm must fly a flag of clear distinction. Burson picked the skull and bones of death to integrated chips. They build up equivalents from discrete devices, be it for gain, as current sources, output buffers or voltage regulators. Their HA-160 is filled with discretion and fully discrete. This includes the Burson-built 24-step attenuator with <0.1% metal film resistors and a custom taper optimized for this amp; Burson low-noise super regulators; and Burson discrete op-amps for the output stage.

The HA 160 thus showcases all of Burson's in-house solutions which are available also to DIYers and OEMs. Its class A circuitry is packaged in a 6 mill clear-anodized sandblasted aluminum case to abscond with large conventional heatsinks and turn the entire enclosure into one. This allows for a higher idle current, richer class A bias and lower distortion. The substantial panels are also meant to combat microphonic resonances. The differential input stage eliminates signal-path capacitors, the push/pull output stage runs two pairs of A1930/C5171 Toshiba transistors for up to 2 watts of speaker-level power. There are two large Nippon ChemCorp. 63V/10.000uF storage capacitors and 14 smaller silver mica caps. Core specifications include an i/o impedance of 47K/5 ohms respectively, frequency response of 5Hz to 35kHz (-0.3dB/-1dB), S/N ratio of >98dB, channel separation of >70dB at 10kHz, power dissipation below 10 watts and output power of 650/800mW into 300/60 ohms. Weight is 6kg and dimensions for the case are 280 x 110 x 44mm.


During the design process, the team aimed for proper drive into what were then considered the toughest headphones, Sennheiser's open-backed 300-ohm HD650s. The rationale was simple. If it could handle those, it'd handle anything with equal grace. I'd substitute HD800s and AKG's K-702s to test drive.

The single pair of RCA inputs, IEC power socket with mains rocker and international voltage switch on the rear are self-explanatory as are the volume control and tiny blue power LED on the front. Being unmarked, the outputs aren't entirely but optimized for different impedances - 15 to 150Ω on the left (low), 150 to 500Ω on the right (high).