Walter is one of those super smart and innovative guys who happened to make musical instrument gear. It was a treat to get to know him a bit back in the day. Just like our own favorite wizard Ron W these guys are very inspirational to hang out with. Walter moved to the high dessert of SoCal several years ago - Palm Springs area - and I haven't been in touch with him in many years. I don't know if he's still building these amazing boxes or even if he's still with us. Hope so! Each one is built by him and by him only, as far as I know he never had any staff.
The Alembic power supply version of his front panel was something I may have talked him into way back when. I even convinced him to make the 1/4" input jacks FX loops (ring out, tip return) so I could insert a chorus pedal on the bridge channel only. I do remember him grumbling about these mods and I can't say how many of these front panels he actually produced. My guess is less than 5 despite being included in the flyer above. Mine is an "amber light" version so 400/600W.
These Class-D amps were among the first ever made for musicians. People were shocked to learn the little box could produce so much sound. Apart from the surprising wattage, light weight, and super-wide EQ range, they may not have very hi-fi specs. But the circuit design feels "fast" if I can describe it that way. Like instant transients. And they became quite popular with traditional jazz guitarists and upright bassists. That 5-pin connector made it very popular with me!
Jazzy, that one for sale has one unusual feature on the far right of the front panel. Some of Walter's amps have an XLR output and some have 1/4" jacks. This one looks like it was changed from one to the other and I'm not sure it was a Walter mod. Oh and the operating voltage is switchable via a small switch hidden in the center of the heatsink fins. You can almost see it in the photo of the back of that amp.
They're great little amps.
Jimmy J