Four your consideration, one pair of Amp Camp Amp (ACA) monoblocks with upgraded power supplies. I am still astonished by how good these amplifiers are giving credence to Nelson Pass’ philosophy that the “first watt is the most important watt.” I purchased them to play around with high-efficiency speakers i.e. Zu audio, and Klipsch Cornwall’s. I no longer own any high/mid efficiency speakers, so these are not being used. This pair was built by amplifier designer Justin Weber of ampsandsound. The upgraded 19V power supplies were ~350 alone and take these babies to a whole new level. There are plenty of resources online providing specific details on these should you have any questions about their design.