The one I had used AD843 opamps, a 5a/36v sigma 11 power supply, and some beefier heat sinks, 6 channels, and cinemag cmli 15/15a input transformers. Colin can detail what he biased everything to. It was built to be able to drive speakers, tho by the end, I'd moved it to preamp/headphone amp use. I do think even the stock 3 channel build with a good power supply would be quite satisfying.