Tubes on Proac 1.5's

I don't know a lot about the different tubes and it's really great to hear these many opinions. I'm leaning towards a VTL MB125 mono setup.

While some of you mentioned KT88's I need to know if this is just a tube swap for EL34's (sorry REALLY green here!)

I just borrowed an older Sonic Frontiers 40watt tube amp and my wife and I are stunned by how much "percieved" power this amp has. The Classe' is more refined with more bass slam but the tube sang along really nicely.

I must learn more......

Thanx for the replies

The bass is really quite acceptable with the sfs 40. Now I don't know which way to turn.