Check out www.passlabs.com for solidstate single-ended Class-A designs by Nelson Pass. I have build his balanced Zen preamp and am currently building 2 Zen power amps for bi-amping. Does anyone know where I can get custom enclosures for Class-A power amps. I currently have 5"x10.5" heatsinks and want to build enclosures with them. I now want want to construct a couple of power amp enclosures by attaching a face plate, back, top, and bottom to a couple of approx. 5" x 10.5" heatsinks. OR I may want to have my power supply in a separate (standard) enclosure. If this is the case, I will probably use the two sinks (per amp) as the top not the sides. I purchased my preamp enclosure from Spire Audio, but it seems that they are no longer in business. Any suggestions?