A note on REL subs...I have 2 of an older generation of these, a Q150e and a Q108 II, and upon taking them apart to tighten stuff and look around, I've noticed they are very well built torroidal transformer based amps assembled to a very high standard, and they sound great…exactly as designed. Nothing "cheap" about them. The REL's high level input of course does take the speaker signal and reproduce at least the lower range that the power amp is sending out (tube in my case) regardless of what the mains are doing, and small driver mains like the LS50 aren't expected to create earth shattering bass anyway…I use mains with 2 powerful small drivers (plus single tweeters) in each that naturally roll off below a certain point (you have to drive the crap out of them to get them to give up, so they don't get over driven unless subjected to accidental drunken "knob turner" abuse) and that's how it should work. Leaving the mains full range utilizes the speaker designer's mojo, and the RELs job is simply to energize the room and provide the lower octaves if you want 'em. I defy anyone to detect tonal aspects in RELs that aren't from the amp, as hey…it's all low range of course and to my (working professional sound tech, pro guitar and bass player) ears seemingly neutral…they might have a tone of their own but my 2 RELs, albeit with a different output and driver size, are absolutely identical tonally, and they don't seem to noticeably add anything to whatever tone character the amp sends to them.
