Speakers that are good with tubes

Relatively speaking high powered tube amps don't sound very good. If one is going to bother to search for efficient speakers with benign impedance curves I'd suggest looking at medium to low powered amps. Just my opinion of course,

Sonus Faber

Wilson

B&W

Most speakers. But the speaker needs to be matched to appropriately powerful amp. Not a 15 wpc amp with 82 db efficiency speakers. I doubt 300 wpc amp with 105 db speaker would be an ideal match either. 

Hilde nailed it

All tube amp got issues to control bass driver , because output impedance much more higher co compare solid state amp. You hear bass less articulate and more fatty .I say only speakers with active bass is ideal for music reproduction ,using tube amplifier.  You can see some brands included horn speakers but not to many on the market (my brand included)