Woo Audio WA 22 Headphone Amplifier (Playback 43)

Equipment report
Headphone amps and amp/DACs
Woo Audio WA 22 Headphone Amplifier
Woo Audio WA 22 Headphone Amplifier (Playback 43)

headphone universe who are less well known to traditional audiophiles. I’m thinking, here, of manufacturers such as Apex (TTVJ), Blossom Audio, Burson Audio, Darkvoice, Headroom, Meier Audio, Ray Samuels Audio, and Woo Audio. And to be frank, even this brief list is only scratching the surface, my point being that headphone electronics are a different world entirely than conventional audio electronics.

Driving Headphones: A Different Challenge Than Driving Loudspeakers

There are other differences between headphone amplifiers and amplifiers in the traditional audio realm. These are worth reviewing because they set the stage for the potential contentious remarks to come later.

First off, it is important to understand that many of the accepted truisms regarding tube-type power amplifiers vis-à-vis loudspeakers no longer apply when we talk about using tube-type headphone amps—such as the WA22—to power typical headphones. For example, it is common knowledge among audiophiles that tube-type power amps can give “interesting” (and in some cases downright problematic) results when interfaced with certain loudspeakers, largely because various tube-amp-output-impedance-to-speaker-input-impedance matching issues can arise. These issues are compounded by the fact that speakers typically do not exhibit flat impedance curves, meaning that impedance matching problems may occur at some audio frequencies, but not at others.