I'll add to this old thread with another more extreme option. I'm using 1.25 watt from a 46 tube for my 16ohm Valencias, I do have the option to use a 45/2a3 but the 46 sounds so nice. I do use a powered subwoofer swarm so that helps if the 1.25 watts isn't enough to push the 15 inch driver. I'm using Werner's crossovers with a super tweeter. I don't listen very loud so that makes all of this possible.