I had a very similar experience with my M60's driven by Denon avr-989 at 115 wpc through a PS3. So I used an SPL meter to test it out and it was playing at 99 db 13' from the front speakers. I guess the M60's play so clean that they seem to be less loud than they actually are (yeah, not very scientific, I know).
The other thing to consider is that when you are playing a BD, you are using 5 channels (5 X 115 or whatever), whereas stereo is 2 X 115 wpc so there is less sound pressure in the room. If you were to listen to your CD's using 5 channel stereo, I think the loudness would be close to what you experiencing through the blu-ray.
