I built two of the Sound Values/Sound Valves Amp kits and a Van Alstine PAS 4SI preamp kit. The preamp kit was a blast to build. I was supposed to send it back to Frank for a free bench test. I didn't do it, I crossed my fingers and turned it on. It has worked flawlessly since new. The Soundvalves is a different story. Not as much fun to build. One started acting up, I tried to call the company, but they went belly up. I talked to Frank personally and he warned me they were an unstable circuit. I still use one today but the bias won't adjust to equal out the lights. I suppose it is a simple fix. I built this stuff in 1997.