I'm using the Pass Labs X250.5 with my Jr.'s in a 15 x 12 x 8 room and they sound stunning. I filled each speaker with 50 lbs. of lead shot like you're supposed to do. Tons of punch and bass, but not boomy or overbearing at all. I use a Simaudio P-5 LE for my preamp, and Signal Cable Silver Res for cables.