Those amps look very much like the
AVA Ultravalve.
They share the general layout of the ST-70, but have different circuits. If you've built one of those, you might get something out of the long write up that I linked.
I've heard them and thought they were good in the sense that they did nothing objectionable, and they don't seem to have that toob amp sound. They could easily power SongTowers or HT2-TLs.
They're priced a bit rich for me. For the same price of $2000, you can have one of those, or a 225 wpc solid state amp, an
AVA Synergy 450, that can drive just about any pair of speakers.