I have pretty sensitive speakers (95+, Audio Note AN-E SPe HE and Pure Audio Project) and they both sound phenomenal with a 300B Audio Note Meishu Tonmeister Silver (around 10 WPC)
If you don't want to deal with tubes, I had a Pass Labs XA25 and a couple of First Watt amps (17-25 WPC) that are lower power Class A SS and they were also fantastic, particularly the XA25 at 25 WPC into 8 Ohms

