In no particular order there are: A Conrad Johnson Sonographe SA150 or SA250, or even better for a little more is the CJ MF2100. All are about 125 watts at 8 Ohms.
Next there is the older version Bryston 3B and 4B amplifiers, still under warranty (20 years transferable) Check the age with Bryston before you buy (ask seller for the serial number). They've made these for many years. I think the newer ones are 3B-NRB, etc. Not quite sonically up to the ST amps, but very very good for $500.
Also look at Acurus A150 and A250. Acurus does make some multichannel amps as well.