Since we don't have a thread dedicated to general DIY power amplifier discussions, I figured I would start one... Some time next year, I'm moving back west and I'll be far closer to my father. Following my move, I plan to build a set of speakers and an amp. For the speakers, I'm heavily considering the Nagaoka D-37 mkIII plan that @JK47 and @struggles used. Regardless of whether or not I use Nagaoka D-37 mkIII plan, my speaker requirements will be as follows: minimum of 94.5 dB/w/m, highly resolving at low volume levels, plays nice in a small room (regular den/ bedroom). I'm looking for suggestions on DIY amp designs that will play nice with those speaker requirements. I don't have the electrical knowledge to spearhead a project like this on my own, but my father spent most of his career as an electronics R&D engineer, and certainly does. This'll be a nice learning experience for me and will give me solid quality time with my father. The basis of what I'm looking for are: Low watt output is preferred BJT amplification, no FETs No coupling capacitors 20 to 20kHz response: -0.1 db 2 to >= 45kHz response: -3.01 db Constant phase shift over 20-20kHz (provided phase shift is listed) ...these specs look a fair bit like the new Vidar out there. Also, banning MOSFETs from the design eliminates Nelson Pass designs.