Disclaimer: The Woo Audio 2 has been in my listening room for a long time now and I specifically only wanted to write a review on it after an extended period. Long story short, this isn’t an official review sample, it was fully paid for.
Woo Audio (2)
I don’t really think Woo Audio still needs an introduction as I’m pretty sure every single headphone enthusiast out there has at least heard or read something about their amplifiers once before. Those who haven’t probably were abducted by aliens or something similar and as they have suffered enough I’ll do a short intro just for them: Woo Audio is an American based company located in New york making high-end amplifiers having over 40 years of experience. The most famous models are the WA3 and WA6 but they have a lot more products like the WA22, WA5 and the WA2 we’re looking at in this review.
The WA2 used in this review is a highly upgraded version of the stock WA2 featuring Black Gate Caps (+$400) and a Goldpoint stepped attenuator, options I think are no longer available when ordering today. This shows the WA2 is not a new amp but since the beginning it has been a popular unit all over the world and so it deserves a review.
Gorgeous. Sexy. Powerful. The first three things that come into mind when I look at the beautiful Woo Audio 2. If there’s one thing most people agree on it’s that Woo knows what style is. Woo uses a full aluminium die-cast chassis with an anodized finish and it’s available in black and silver. While the amp looks great in pictures, I can assure you it looks even better in real.
The build quality of the WA2 is exceptional, it is heavy and not the slightest flaw can be found: it doesn’t wiggle on its feet and all screws and buttons are perfect. It looks bigger in real too, it weighs about 17lbs/8kg and it’s the best packaging I’ve ever seen: I have even read a post on Head-fi of a guy who took it as hand luggage on a 747! Not only the outside looks great, the inside, with its point-to-point soldering and clear lay-out looks professional and good.
The WA2, is a SET OTL amplifier: Single Ended Triode amplifier with an Output Transformerless design for the higher impedance headphones (in theory). It features not one but four inputs and one RCA output on the back as it also is a pre-amplifier. On the front you can find the power switch and volume/input selector together with the single ended headphone out.
The Woo Audio 2 uses six tubes in total and that gives you hundreds of possibilities (if not more) for tube rolling. It has two of the extremely popular 6080 power tubes, two 6922 type driver tubes and two EZ80 type rectifiers. In the beginning I rolled different tubes in the WA2 but I fairly quick found a combination I love: RCA 6AS7G + Philips Miniwatt + Siemens 7308. If you check Google for WA2 tube rolling you will find a huge amount of suggestions but the most returning tube is the 5998 power tube. I did have that tube in for the first few months but the more I listened to the 5998 in the WA2 and 339 the less I liked it. They were all replaced with the warmer sounding RCA 6AS7G and they make me enjoy my music a whole lot more. The WA2 doesn’t need the 5998 unless you really want to use it for the planars (more on that later) and in my opinion it makes the WA2 too forward sounding, it doesn’t like the extra gain to my ears. I know a lot of people agree with me on that, including the owner of the amp, but most people swear to the 5998 as power tube. I tried different rectifiers like the Philips Miniwatt EZ80, the Mullard EZ81 and Mullard EZ80 but I didn’t find the rectifier to influence the sound that much in this design. As driver tubes I tried a Philips made Siemens 7308, this tube has a clean top end that maintains extension without being bright, neutral smooth mids and wonderful tight bass. Next to that I got some matched 6922 Sylvania tubes but I always heard a slight hum with them from the beginning and as I preferred the tonal balance of the 7308 I didn’t gave them the time needed to burn in before I put them in storage.
All these tubes types are very popular for tube rolling and you could spend a fortune on tubes if you would want that, there are some great suggestions on the www.
But how does it sound?