The WA22 was so dynamic, detailed and even-handed across the spectrum that it was equally at home with all types of music
It is transparent, particularly in that you don’t notice any treble veiling or grit as you do with some lesser headphone amps. Bass is solid, well defined and can be very deep with the right headphones. Tonal balance is very, very good, with no sense of treble roll-off or brightness.
Woo 22 balanced headphone amp which, with the premium tube upgrades, presents the most effortless, immediate presentation of sound I have heard from any headphone system, or perhaps any stereo system.
The Sennheiser HD800 headphones and the Woo Audio WA22 integrated headphone amp configured in fully balanced configuration is one of the best audio systems I have heard. Tremble and midrange performance are as good or better than any headphone or two-channel standalone system I have experienced. Bass is very satisfying and will only be bettered by the very best fullrange speaker and subwoofer systems.
I have since tried HD 800’s with the prototype Woo Audio WA 22 amp (which is tube rather than solid state apm that has variable output mpedance). The WA 22 takes the sense of vividness up a notch, mostly by making the midrange contrast level higher, while introducing minimal if any deleterioius side effects. The mostly subtractive errors noted above are still there, but they are diminished in the overall presentation. This gets me to the level of really, really liking the HD 800s. The HD 800s are so good that I could easily live with them over the long haul. (AVguide Buyer Guide 2013)
* Included tubes: 1 pair of 6AS7, 1 pair of 6SN7, and 1 274B
* Tubes shown on the pictures are not included.
* AC power supply cord, interconnection cable are not included
* Shipping charge applied to CONUS only. International shipping charge will be invoiced when your order is in our system.
Driver tubes upgrade:
Hand-pick matched pair
GE/RCA/Sylvania/Tung Sol 6SN7GT NOS tubes
We tested these tubes in an actual amplifier to ensure the highest quality. $330 (2 pcs) with 30-day warranty.
You get a clean and dense sound image with these tubes. It is very low noise, smooth and delicate in the upper frequency range, deep and solid bass, high clarity.
Rectifier tubes upgrade 1:
Takatsuki TA-274B single $1045 (1 pc) with 1-year warranty
Takatsuki 274B offer ultimate performance to any current production 274B's. Users have claimed that it exceeds the quality to NOS Western Electric 274B.
The TA-274B sold in an individual package Click to see details.
Rectifier tube upgrade 2:
Sophia Princess Mesh Plate 274B rectifier $160 (1 pc) with 30-day warranty
Wide open soundstage, full body, silky smooth, a great combination with the above tubes. Buy and ship independently.
Sophia Electric™ 274B tube is a premium rectifier tube for a 5U4/5R4/5AR4 direct replacement with 3X longer plate structure, thus it has a deeper, wider sound stage and even smoothier sound than Mullard 5AR4.