I'm assuming that your running the Perreaux PMF-2150B, as the model number didn't quite turn out correctly in your post. If i remember correctly, the RS-1B used two 10 inch "dual drive" Watkins woofers per box. If that's the case, your talking about a relatively tough load between the woofers impedance peaks and the amount of reactance due to the motor design of the woofers being used. Based on that, my suggestion is to look for a Perreaux PMF-3150B. Hang onto your 2150B until your completely sure that the 3150B (or whatever amp that you do decide to check out) will do what you want it to do. You can unload whichever one you don't want after that. The 3150B is rated for 300 wpc @ 8, but sound EMINENTLY more powerful than the 2150B while having WAY more slam and bottom end impact. Quite honestly, it makes the 2150B sound kind of "anemic" and quite "forward" in comparison. I have owned 2150's and currently own two 3150's and there is NO comparison when it comes to "oomph", warmth or bottom end impact. Quite honestly, the 3150's have more bottom end impact than any of the other BIG amps that i own. This includes, but is not limited to, the Sunfire Signature (1200 wpc @ 4), the "standard" Sunfire (600 wpc @ 4), SAE 2600 (600 wpc @ 4), modified Phase Linear 700B (500 wpc @ 4), B & K M-200 monoblocks (400 wpc @ 4), Nikko Alpha 450 (400 wpc @ 4), Forte' 6A (350 wpc @ 4), modified Phase Linear 400's (350 wpc @ 4), Forte' 3 (350 wpc @ 4), Acurus A200X3 (300 wpc @ 4), etc.... For the record, i've also owned the Bryston 4B series (400 wpc @ 4), Classe' 200 (400 wpc @ 4), Adcom 5800 (400 wpc @ 4), Yamaha M80 (400 wpc @ 4), the biggest Onkyo amp, various Crown's, etc.... You get the idea. I'm not trying to sound like a "know it all", but simply wanted to give you some background info so that you know EXACTLY where i'm coming from. Most of these are "big brute's" and relatively conservately rated when it comes to power output. This is especially true of the SAE 2600. I used to use it to power multiple "bass bins" when doing Pro Sound reinforcement several years ago. It too would be a good candidate for your system (if you could find one). One observation that i've made over the years is that amps that use the "old style" iron core transformers typically have better bass charactersistics than do similarly rated amps using toroidals. The only other amps that i have been told (from various reliable sources) that will challenge the 3150 on bottom end output would be SOME Krell's ( not all models ), the Aragon 4004 / 8008's, the Eagle amps ( especially the 7's) and the larger Perreaux PMF-5150B. While i'm not directly familiar with it, the John Curl designed Parasound HCA 3500 might be worth checking into. While it does use dual toroidals, i have faith that John knows what he is doing when it comes to building an amp. I'm sure that there are several others out there, but these were some that were specifically mentioned in conversations that i've had with other very experienced "gearheads". Hope this helps and puts things in a little bit better perspective for you. Sean >