I would consider Linear Tube Audio LTA products. I have owned both Quicksilver and LTA to drive Zu Audio and loved them both. Quicksilver a little more typical tube sound while LTA loses the syrup and exchanges it with clarity, inner detail but keeps the smooth and fatigue free presentation.
Compact ~20WPC Tube Amp
I should say 20WPC or more....
I’ve been trying to use a 8WPC 300B SET (Sun Audio) with some vintage bass reflex studio monitors from the 70s (96dB) and it’s clear that I need a bit more power. Everything sounds really awesome but the highs will distort at anything beyond low-medium volume which has been fine but I want to play a little louder sometimes!
Space is limited so I need a stereo amp or maybe small monos are possible.