by Frank Iacone

Woo Audio is a family business founded by Wei Wu and his two sons and the company has been making amplifiers in New York for the past 10 years. Wei has been designing tube amplifiers for over forty years; his sons Jack and Zhivong also design and build amplifiers, though Jack’s main responsibility is to market and promote Woo Audio products. The company has been very successful in the headphone community and have built a reputation for manufacturing products that are overbuilt and priced competitively.

Woo Audio designed the WA5 to be the ultimate headphone amplifier. The WA5 is a single ended triode, designed around the legendary 300B tube and uses two 6SN7 tubes to drive the 300B (Shuguang 300-98B are standard). A full tube power supply in a separate chassis uses 5U4G tubes for power supply rectification and a supplied umbilical cord links the amp to the power supply. The unit weighs in at a hefty 70 pounds for the two pieces. The WA5, like all other Woo Audio products, is manufactured in the United States in New York and until the  release of the WA234 mono-block, it was the flagship in the product line. The amplifier is priced at $3500.00 with the stock tubes supplied.

The WA5 is available in two versions. The “other” version is the WA5 LE, which is for headphones only, while the WA5 (reviewed here) is more like two separate amplifiers in one package; it has outputs that will drive efficient speakers and also includes a separate amplifier for headphones and will drive any headphone currently manufactured — except an electrostatic design.

The dual chassis (each are identical) construction is rock-solid and the build-quality is such that it really seems like they’ve taken great care in using all high quality parts with the amplifier.  There’s a rail designed as a handle so that the amplifier can be easily lifted — a unique design. The switches used on the front panel are all manufactured to tight tolerances and move fluidly. The front panel lets you switch from XLR to RCA, and low or high gain in order to tailor for each individual headphone you might be using. The speaker switch activates the speakers. The amp has three RCA inputs in the rear of the amplifier and will accept either spade or banana connections for speakers.  The rear inputs are all single-ended.

The amplifier is a work of art and looks it; it’s a conversation piece that begs to be displayed in the open. People who visit my home always ask what it is when they come in, and when I explain to them what is, their next question always is “Well, what does it sound like?” It’s really nice — all of it. When looking at the bottom of the amplifier, the feet used were also uniquely designed to provide support on any rack or stand you place it on. The amplifier is hand-built using no printed circuit boards and uses all point-to-point wiring.

Equipment Used for the Review

The speakers used for this review included the Omega 3T monitor and the Fritz Carbon 7 SE monitors. The cables used were all Nordost Blue Heaven cables. I chose the Oppo BDP 105 for the source.  The stock tubes were also used, but I did do some tube rolling and ended up settling on EML 300B tubes priced at $550.00 for the pair. The driver tubes used were both Tung Sol 6F8G flat and round plate matched-pairs, NOS tubes from 1942 manufactured for the US Army Signal Corp. The rectifiers included some RCA 5U4G NOS tubes and a rare pair of USAF 596 tubes. This tube compliment added another $900.00 to the cost of the amplifier, making the upgraded WA5 retail for $4400.00.

Music included both high-resolution audiophile recordings and SACD recordings. I also used both female and male vocal recordings.  Jazz, Pop, folk and classical recordings were also used during the evaluation. The variety included everything from dance to mellow jazz recordings.

Sound with Speakers

I installed the amplifier with the stock tubes and hooked up the system with the Omega 3T speakers, turned it on and pushed play and I knew immediately that this amplifier was special. The sound with the stock Shuguang tubes sounded very transparent. The Omega 3T is a very detailed loudspeaker and with the WA5, the sound was organic and musical. At 94DB, the 3T was very easy to drive with the WA5; the amp had enough power to fill my entire den with sound, which is fairly large room (15′ x 20′).

I felt that amplifier was able to extract everything that the Omega had to offer. I could hear clearly the drum and cymbals with crisp articulation, and very distinct transparency in vocal performances. The sound stage was very wide and deep and the acoustics of the recording venues were easily identifiable.  The same was true when I switched to headphones — I could hear very deep into the recording.

Switching to the upgraded tubes, the EML 300B, Tung Sol 6F8G and USAF 596 together really showed what the WA5 was really capable of. The sound stage expanded and the focus became pinpoint, with even more apparent air and separation between instruments. I lost myself in the music completely, whether I was listening to headphones or speakers.

When I met Fritz Heiler of Fritzspeakers.com in Denver at RMAF, I asked him if a 300B amplifier could drive his speakers: he told me they would drive them easily. Interesting, because the Fritz Carbon 7 SE monitors are 88dB. Fritz shipped me the pair he showed at  RMAF to use for this review, and I was shocked at how easily this $2500 reference monitor was being driven by the WA5.

The sound of this speaker is spooky and really showcased what the WA5 was capable of doing with a more expensive high-end speaker.  The bass extension on the Fritz monitors goes down to 32Hz; the Omega 3T bass extends to only 60Hz, so this was a huge improvement in low end reach.

The WA5 with the Fritz speakers really made the soundstage come alive. Using the speakers nearfield gave me a sharply focused midrange; I wanted to hear more and more vocal recordings. Listening to Sara K excellent Chesky recording Play on Words the track “Burning Both Ends” was vivid and seductive. The tonalities of the instruments were very accurate and easily identified in their proper place in the soundstage, for example, I could hear the violin coming from the rear of the sound stage very distinctively. The music was so exciting and the performance exceptional and I felt as if the speakers had evaporated.

Badi Assad’s Echoes of Brazil recorded on Chesky is another outstanding acoustic recording, and Badi’s guitar on track 2 “Abismo de Rosas” is so transparent and I found the tone completely seductive. I could hear her hand going up and down the strings, yet the Fritz speakers made it sound so delicate and alive.

Rogers Waters excellent “Amused to Death” let me hear all the detail that was available with the Fritz Carbon 7 SE. The album is a showcase for different sound effects and the WA5 did not mask any of it, but I could only focus on the performance and realize what a great piece of music Waters had created.

Headphone Listening

The WA5 has a low and high impedance switch on the front panel plus the XLR input for use with difficult to drive headphones like the AKG K1000 and the Hifiman HE6. Not necessary with the Sennheiser HD800, but that headphone does have a reputation for being very fussy with amplifiers; happily, the WA5 was up to the task and brought out the best that the HD800 had to offer. The instrument separation on Badi Assad Echoes of Brazil was upfront, but not in a bad way. I could hear the musicians on different tracks on this recording with space and separation, much like what I hear when attending live performances. The sound of her guitar was so delicate and her playing so flawless that it was easy to get lost in the music.

Junior Wells Come On In This House is a wonderful acoustic album. On the track “What My Momma Told Me”, the slide guitar work is exceptional and I was able to follow with Junior’s voice and not lose track of the slide guitar playing throughout the track. The performance is so alive. Whatever headphone I used on this album, the WA5 was able to really engage me with the listening session. The HD 800 spread out the musicians in a very defined soundstage.  Switching to the Beyerdynamic T1 presented more focused images within the sound stage.  The T1 and HD800 were both exceptional and each headphone has a different set of strengths. The WA5 easily was able to distinguish those differences: the T1 had the smaller sound stage, but had more bass impact and better focus where the Hd800 had more accuracy, a the wider soundstage and greater detail retrieval.

The Fostex TH900 had very similar transparency using the low setting on the WA5. For this, I switched to Harry Connick’s We are Love, a vocal and musical masterpiece with truly vivid vocals. Recorded by Harry Connick with some outstanding musicians, this is one of my favorite recordings. With the Woo Audio amp, the TH900 easily portrayed Harry’s voice with exceptional clarity. The sound stage was equally impressive. I could hear the drum brushes very distinctly on Track Two, “Only ‘Cause I Don’t Have You” and was easily found in the rear of the sound stage, with Harry centered up front.

Switching to Track 6, “A Nightingale Sang in Berkley Square”, gave me goosebumps; Branford Marsalis haunting tenor saxophone was so real and alive. The bass player opens this track to the left and Branford is in the rear of the soundstage on the other side of the stage behind Harry. This is one of the most exciting jazz tracks to listen to as Marsalis’s playing comes alive on this recording, and this amp/headphone pair just nailed the performance. You can hear every breath of air being blown into the saxophone. The album is a treat and performance not to miss.

The HiFiMAN HE6 has a reputation (and deservedly so) as being the hardest headphone to drive — a 83db sensitivity makes it a difficult load for any amplifier to drive. The HE6 has given many amplifiers problems, and even took out one of my amplifiers while trying to drive them in the past, but the WA5 proved it was up to the task. Utilizing the XLR 4 pin jack that was designed for the AKG K1000, the WA5 was able to drive the HE6 easily. The HE6 had sufficient power and really opened up when I used the WA5.

Copland’s Fanfare For the Common Man, recorded on the Reference Recording label and mastered by the legendary Keith Johnson, is very dynamic and will challenge any headphone and most speaker systems. The Decware Taboo Mk11 that I previously owned completely collapsed when trying to reproduce this recording with the HiFiMAN cans, but the WA5 sailed through and at no point was the amplifier under any stress. There were no signs of clipping and the performance was as good as I have heard it reproduced.  The HE6 can perform as well as any flagship headphone when driven properly and the WA5 proved to be the best match for these headphones I have experienced. The WA5 easily drives the HE6 and scales it to heights I have rarely heard before while using this headphone.  The HE6 and WA5 sounded spectacular together.

The Audeze LCD2 and LCD 2.2 both sounded excellent being driven by the WA5. I tried both headphones on the low setting and also used the XLR 4 pin connection. The planars sound excellent either way. The LCD headphones are easier to drive than the HE6, but can also handle up to 15 watts of power. The low setting putting out 1.5W was sufficient to drive both of these headphones effortlessly. The XLR gave them more power and the planars handled the extra power without any problems. The choice of using them either way is a nice option to have depending on each individual listeners preference.

Conclusion

The WA5 had been in my system and in constant use for the last five months. It is a work of art; it is both magnificent to look at and a true reference amplifier. Whether I was listening to headphones or to speakers, there were no shortcomings. The build quality and selection of parts used to build this amplifier are excellent. Woo takes great pride in their products and the WA5 was their first reference amplifier. It has received high praise from both professional and music lovers for having exceptional sound. The WA5 has really stepped up the performance of all headphones I tried it with. The WA5 is a true end -game product. If you are looking for an amplifier that can play efficient speakers and any dynamic headphone with exceptional musicality, then theWA5 could be just the product you are looking for.

The WA5 offers exceptional transparency and is a tube lovers dream and has many excellent choices for rolling. It really brought my listening experience to another level — mainly to one that just let me listen to music as the WA5 is the most musically engaging amplifier I have had in my system and provides endless hours of musical bliss. It is highly recommended for anyone looking for that end-game amplifier. Purchasing the WA5 review sample was an easy decision for me. It is one amplifier that will reside with me permanently.

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