Keep at it. I admit that I buy class D but if it's DIY I like MOSFET A/B designs.I built this amp and it works quite well and seems pretty bomb proof. https://sound-au.com/project101.htm One problem these days is that you can not reliably get the Hitachi MOSFET's anymore. The vast majority found online are fakes. Luckily you can get a very similar new Exicon ECX10N20 and ECX10P20 directly available from Profusion PLC in the UK and they will be drop in replacements in many cases (not sure about the OP's design as it seems to be optimized for the Hitachi parts).