Why You Can Trust CNET Woo Audio WA2 headphone amplifier review: Woo Audio WA2 headphone amplifier
To put it simply, the Woo Audio WA2 is the best headphone amplifier in its price category by a mile. It provides an experience that is completely luscious -- deep, smooth bass, rich vocal reproduction, and a sweet, spacious, notably airy treble that's smashing for live classical performances, although can handle anything you throw its way. Superb
We don't subscribe to the belief that older is always better in the audio world, or that the only way to enjoy high quality music is from vinyl, through a vintage valve amplifier, with £300 interconnects. What's important is that it just sounds amazing.
Woo Audio WA2 headphone amplifier
The Good
The Bad
The Bottom Line
Woo Audio hand-build and hand-wire ultra high-end headphone amplifiers using vintage valve amplification. Whether valves are better than transistors is like asking whether dogs are better than trees -- it's down to preference, and ultimately, what sound you're after.
But a headphone amplifier is highly recommended for higher-end headphones, just as a 1080p plasma HDTV is recommended if you're buying Blu-ray discs. The Woo Audio 2 is in the middle of the Woo Audio amp range, and costs around £640 direct from the manufacturer's Web site.
Design
Each hand-built WA2 is as stunningly impressive visually as it is tank-like in its construction. The entirely anodised-aluminium chassis has been meticulously designed and built with care, but does get fiercely hot thanks to the burning-hot tubes. Fatman's iTube 452 came with a removable metal cover to shield you from burns or knocks, but the WA2's tubes offer no such protection.
A single 6.3mm headphone jack sits on the front, to the left of a large volume knob and source input controller -- both also cast from aluminium. The tubes themselves come in separate boxes when the amp is delivered and must be fixed manually. It's easy, and allows for an upgrade or replacement in the future. Woo Audio also offers various tube upgrades at the time of the purchase order.
Features
This isn't an amp for your average earphones, as most are designed to be portable and powered by low-power devices such as iPods. The WA2 is geared towards full-sized hi-fi headphones with impedance values between 30-600 Ohms, and it'll handle frequencies between 8Hz-100kHz.
Four pairs of stereo RCA inputs live around the back of the system which can be selected with one of the aforementioned huge knobs up front, letting you wire up a CD player, DVD system, docked iPod and laptop, concurrently.
Seriously, what do you think you're paying £600 for?
Well, since you asked, an integrated valve-based pre-amp -- and a pre-out option if you want to send the pre-amp signal to a separate amp. This is unusual for headphone amplifiers, but with the combination of multiple inputs and the functions of a valve-based pre-amp, you get a glimpse at the bonuses the WA2 offers over similarly priced competition.
Performance
We spent two months with the WA2 before putting our thoughts to paper, during which time we listened for hours, daily, with a range of headphones, including Denon AH-D5000 and AH-D7000, Sennheiser HD 650, AKG K 701, Audio Technica W1000, W5000 and AD700, and more recently the Grado GS1000s, to name some favourites. And of course SACD was used where possible.
The hype this amplifier receives is highly justified, with truly divine sound quality across the board. Its deep, powerful performance with the HD 650s were particularly enjoyable, along with the K 701s and both Denon models mentioned.
If we had to pick a single word to describe the Woo Audio experience, it would be 'luscious' -- deep, smooth bass, rich vocal reproduction, and a sweet, spacious, notably airy treble that's smashing for live classical performances. Switching to even a £250 headphone amp will make a huge difference over the integrated headphone amps on a modern hi-fi amplifier, but the WA2 pushes this difference into a new dimension.
Listening to Mary Black's 1989 studio performance of Columbus, for example, was one of the defining moments when testing the WA2. Not only was her naturally beautiful voice delivered more perfectly than we've heard before, but every aspect of the recording was too good not to grin to during listening. The double bass produced notes astoundingly deep at times, yet remained under perfect control, and the hi-hats, violin, guitar and delicate drumming were spine-tingling in their clarity and presence.
But our listening wasn't restricted to music typically enjoyed through gear like this -- we listened to just as much hard dance, brutal death metal, even classic recordings of Balinese gamelan, as we did jazz and the entire career of Pink Floyd. There was nothing we found the amp couldn't handle as well as other amps, but many it could handle significantly better. Feed it vocals, jazz, orchestral, soul, folk, country, easy listening, even R 'n' B, hip hop and dance, and you're in for a treat.
Conclusion
We're used to to the sound of our most highly rated headphones through our existing, impressive-in-their-own-right amplifiers, but the WA2 breathes phenomenal new life into even the greatest headphones on the planet, our favourite for use with this setup being the Sennheiser HD 650s or Denon AH-D7000.
It may not rise to the greater heights reached by the more costly Woo Audio gear, but at this price point it blew away everything we've ever heard. Highly recommended.
Edited by Cristina Psomadakis