Reimer Speaker Systems, Reference 3A & previously mentioned Omega Speaker Systems are some companies manufactuering fairly efficient monitors that you might look into. Merlin might be another. But D_edwards & Audiokinesis are right, there are only a few unless you are willing to go DIY route & that only adds a few more.
See: http://www.welbornelabs.com/recomendspeaks.htm
IMO, crossover slope is the major limiting factor. Tubes do not like third & fourth order xovers & second order xovers should be limited to larger push-pull amps rather than flea watt SET amps.
See: http://www.welbornelabs.com/recomendspeaks.htm
IMO, crossover slope is the major limiting factor. Tubes do not like third & fourth order xovers & second order xovers should be limited to larger push-pull amps rather than flea watt SET amps.