Bel Canto S300 driving Gallo 3.1s

I have tried reversing the polarity, but it didn't seem to make improvement at all. Maybe it is just an over expectation on my part, but I thought the Gallos would have bass that you can feel in your chest. I don't get to that until I am -15dbz off max on the pre3.
I wonder how much my room might have to do with it. The floor is carpeted and the room is about 18' x 28'. Maybe too big?
It isn't that they don't get loud...they do, it just seems like I have very little overhead left and I am afraid of getting some distortion and blowing something.

Marty, that is exactly my experience. I have the Transporter set at 100% volume and when the pre-amp comes up at 50, I can barely hear it. By the time the display hits 80, it counds pretty good, but not earth shattering at all. at 95 it sounds very good and has good power, but I believe I am 5dbz away from maxing it out, hence no headroom and possible disaster at any moment. Am I right to be worried about running at that level?
Everest, I really really like the Gallo's and want to hang on to them. I might change the room that they are in, or maybe the amp.

Okay, with the front display reading 95 on a good FLAC (Breathe-Pink Floyd) it sounds very good and is loud...very loud. I am just thinking I shouldn't have to turn it up that far to get the sound...no overhead you see?
My 100W Marshall guitar amp only gets turned up about halfway before it is just too loud...LOADS of overhead.
I don't think the Gallos are really that hard to drive, are they?

Marty,
I put on some Sabbath, Zep and even some Kraftwerk yesterday...good solid FLAC files. I turned the volume all the way up on the Transporter and slowly went up to 92 on the attenuator of the BC Pre-3. It had very good sound and was loud, but not exactly head banging loud.
So you are saying that if the attenuator is turned to 100 (max setting, that doesn't equate to full power on the S300? How do I know when I am reaching danger levels on my amp then?
I am also guessing since dbz are figured logarithmically, maybe being at 92 attenuation (attenuating 8 dbz) is still far away from max power?

Coffeey, totally agree. The Gallo's should be able to handle a lot more than 150 from everything I have read. My point is that I want to leave some operating headroom. I have always been told that it is wise to leave some margin for resistance fluctuation and such. Never want to play at max. Have I been told wrong?