Two class d audio sds-120c amplifiers. 60watts in stereo mode, 240watts in monoblock configuration. i bought first one new in 2015 and used it happily in stereo mode with my klipsch cornwalls. hard to fault the sound. found a second one online this year to try monoblock configuration- wooo that’s a lot of power! i recently found a Naim amplifier which i’ve always wanted to try, so i’m going to try that for a while and let these go. great units! they were manufactured a few years apart so although they are same model, there are some minor differences, mostly cosmetic, didn’t detect any sound differences. they do have some minor quirks such as a clicking noise when shutting down the amps, which i think is just an issue with highly sensitive klipsch speakers, the naim has a loud shut down sound as well. manufacturer didn’t think this was an issue. i found when wiring for monoblock mode per the instructions, they seemed to be out of phase. emailed with support and they said try reversing and that brought the bass back. manufacturer (i believe the owner answers most of the time) is very responsive and helpful. i will separate, $275 each individually. $500 for the pair