my SVS soudns great with my Polk speakers

Venom:

Yes, SVS sets their sights kinda high, and they often refer to "true reference" SPL, which is defined by Dolby Labs as 105 dB peaks from any surround channel, and 115 dB peaks from the LFE channel. If you set your speaks to small, this becomes 121 dB peaks from the LFE channel. All measured at the listening position.

No single sub that I know of (except a DIY sub like the huge Stryke HE15 with 2 15" active drivers and 4 18" PRs) can hit 121 dB bass peaks in the average size HT room.

Actually, SVS is on the verge of introducing a line of box subs that have a better WAF than the cylinder jobs, and one of them will be a "super sub" that will be capable of easily hitting reference levels in the average HT room. It will be considerably more powerful than twin Ultras - they have measured 130 dB at 25 Hz at less than 10% THD, with 5 kilowatts of input. It will be user tunable, down to about 7 Hz. This sub will be for the discriminating listener who requires reference levels from a single sub in a large room. It won't be cheap or small, though.

So yes, SVS recommends dual subs in the average HT room for true reference playback. Considering I can hit 114 dB with a single PC+, I just might be able to squeak out 121 dB with a second one, but I'm SOO not inclined to do this. Reference level playback is just too GD loud for my tastes. I'm usually hitting 108-110 dB bass peaks on playback, and that's plenty loud for me.

Finally, check their website for the PCi line and the CS line. If you have spare amp, the CS line is very reasonable, and if you don't, the PCi line is a great value. B Stock makes it even better if you can find one. My buddy has a 25-31 PCi that he paid $450 for on B Stock and it sounds great.

Doc