When rebuilding a solid-state amp or DIY use Cree rectifiers. The Cree makes no noise like a tube rectifier. Standard rectifiers are noisy- bad news. Coupling capacitors are electrolytic type- not the best for audio. Although most are 10uF, you can use 4.7uF in polypropylene type for superior audio response and no loss of low frequency response. I find 63 volt that are larger than electrolytic caps but usually fit.