ProAcs love tubes. No question. There is a new speaker line from Finland coming to the US soon called Penaudio -- definite tube speaker also. Also listen to Legend and Silverline. The list is much longer, but these are my picks.
best monitor for tubes?
The contenders are Reference DeCapo, Tyler tylos, and anything else you 'Goners with far more knowledge and experience can provide. I have a tube source and tubed integrated, but am open to experimentation (aren't we all!). Bass extension preferred, too, but I know I can't have it all. Thanks!