Thanks very much to all of you who have taken the time to provide your advice and feedback. All the comments have been very helpful, and I guess based on the comments I'm leaning toward upgrading AVR at some point.
I find my sub can be overpowering if it is cranked up beyond fairly low volume (cranked up only about 30%).
The sub I have has the following specs:
Discrete MOSFET
100 Watts RMS at 0.04% THD, 400 Watts peak
35hz-150hz +/- 3db
low pass filter 50hz-150hz (18db/Octave)
high pass filter approx. 85hz
As I said, I find the sub quite powerful, but based on specs how does it compare to the newer subs?
Also, there have been a number of suggestions to calibrate my system with an SPL meter. I've done some searching, and they appear to be quite expensive -- any suggestions?
