Hi Mark
I own a Torus 20 RM unbalanced with 3x7bs sq plugged and everything else (preamp, TV, CDplayer, Bell Box). I mostly listen to 2 channel stereo, so only run 2x7bs on. I now have it plugged into a separate 20 amp breaker. I share Drummermitchell's sentiments, and I am now looking to buy a 2nd Torus 20 RM. I'm just got a pair IB2s. Here's why I would go with the Torus 20. Pricewise, not much of a difference 20 Rm you can get for $2500. The $1700 for 15CS, per amp as a 20 CS ie this price would be $2267, OK you save $133 bucks. The 20 RM can be plugged into a 15 or 20 amp receptable, not sure about the 15 CS or RM.
When I first got it, I had a 4B sst and ran a paradigm studio 60s. With the Torus, big improvement, but still some compression at high spls. Then got the separate 20 am breaker, compression disappeared (that was in the spring). This fall got the IB2s. At low to moderate volumes, superb. At high volumes, it can vary a little with the bottom end, but only on certain tracks. Bass becomes less tight, a more diffuse sound. Could be room acoustics too. I think it's power requirements of the 7B IB2 combo. No change for Micheal Jackson in compression at ear bleeding volumes. Bass is good all the way. Some movie sound tracks at certain spots in the lower frequencies, and the amps are not clipping eg Pirates I. BTW, a non issue for movies; maybe I'm not listening as closely to the special effects or don't care. Can't go wrong with either purchase. No doubt, volume levels are an issue. I guess the problem many of have in this hobby, for me anyways, is you're always wanting more. So why not start now.
Not the comparison you wanted, but in the right direction I hope
(BTW, break in time for me seemed about 2 weeks. When I unplugged it for receptable upgrade ( a week), it took a week to get full bass back watching Jurasic Park. For that reason, demoing one might be tricky. Check out the other testimonies at the Torus website)
Best of Luck
Joe