It's taken me a while to get my ass into gear in housing my vintage Pioneer amps properly, mainly due to the lack of racking real estate. So I haven't heard the C-21 and M-22 as a matched pair properly until today.
In part, I had been perfectly happy with my Densen electronics driving the E-Xs, which require six channels of amplification. The stereo M-22 alone won't do. But since moving the E-IIIR back into place and reverting its wiring for single amping, this presented the perfect opportunity to give the C-21/M-22 a proper listen.
I have three words to describe the thirty-plus year old amps. Oh - my - God
I'm not sure if it's the proper class-A circuit, fully discrete electronics or just my expectation bias, but it sounds remarkably good. Less grainy and less clinical than the very fine Densen B-250/B-350s, but seemingly more self-assured and, well, natural really.
I really REALLY like them with CD replay via Densen B-400XS. I imagine vinyl would sound even more beguiling. But it's early days. They've been playing for maybe 30 minutes. The preamp is stone cold and the power amp is barely up to temperature. More to report tomorrow, and maybe better descriptors than OMG.