I use them as mono blocks driving my Usher BE20 with great result.
Built like a tank, weight like a tank with tube warm sounding with lot of head room. Unfortunately, resale value is not good. People don't seem appreciate Usher gear value. I had 3 of them now sold them all for Carver 180 mono running KT120s. These tube amps match nicely with Diamond DMD tweeter of BE20
Best