TY both for your input.. I failed to state initially that this week I received a used pair of Atma-Sphere Class Ds; they've been running 24/7 since Thursday afternoon..* My initial, quick thoughts on them is that they sound very good, but I can sell them as quickly as I decided to buy them.. I sort of flit about when shopping for amps, and because I'm a slow-hearing musiclover and not a quick-hearing GEA, it takes me a while to recognise some sonic characteristics about particular amps..
I really appreciate some of the Tyr's characteristics, including (1) that huge choke filter in the main PS, (2) that's it's quite inexpensive physically--that is, little money was invested (for me, read 'wasted') in making it LOOK wonderful and that it looks functional, (3) that it's about 90% built in the USA, and (4) that it's fully balanced.. Something I don't love is its widely spaced output jacks--who makes high-Q speakercable that can be split 8"?, and its somewhat high Voltage gain of 26.5dB.
I'm still looking for more reviews.
FWIW, the price of the AGD Duets is higher than I want to spend right now, and the not-doubling-into-4-Ohms power rating of the Starkrimson Mono 25s does not make me think 'high-current capability', but at the moderate levels I listen at, that's probably a foolish feeling.
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* I also have owned for several years and used off-n-on, a pair of slightly improved** PS Audio M1200 poweramps, that always sound good to me but never seem to cause me to smile bigly at the sounds coming from my speakers; I wonder why?
** Excellent coupling caps (MultiCap RTX 'styrenes bypassed with SoniCap Platinum [Teflon]), Cardas binding posts, and some Soundcoat the Thicker on panels that ring or resonate.