$1500 is really cutting off the kind of tube amp you need...around 100 watts per channel. The Sonic Frontiers Power 2 would be a good choice but they're going for around $2000 used, maybe a little less. You might also want to investigate an outboard auto-transformer which is essentially an impedance multiplier to make that difficult load more manageble. You find them here:http://www.condor-connection.org/asog/tweaks/ps/zero/index.html
Good luck...I think tubes and 'stats are the way to go, but you must be careful.
Good luck...I think tubes and 'stats are the way to go, but you must be careful.