Mattsushiba,
My main speakers have a frequency range that goes down to 80 Hz. Knowing that I needed to set the crossover higher than that I tried both 100Hz and 120Hz on my receiver with the crossover on the sub all the way up to get it out of the way. When I ran bass management frequency sweeps with DVE and a SPL meter, I noticed that with a 100Hz crossover I was getting a big hole between 90-120 (it even went silent for a split second). Even at a 120Hz crossover on my receiver, I was getting a big dropoff between 100Hz and 120Hz. This didn't seem right, I figured maybe it was the crossovers of the sub and receiver not meshing right, or maybe it was phase cancellation issues.
I figured what the heck, and tried speaker level inputs. I hooked up my sub to the mains, put put the sub to "no", and set the crossover to 100 Hz on the low pass of the sub.What happened was amazing. Male vocals were suddenly much fuller, and everything sounded a ton better than before. I ran the sweeps again and there was a relatively flat response throughout the crossover region.
I am not sure why this improvement happened, especially when everyone recommends line level inputs, but unless I am lacking somewhere else by this setup, it makes sense, to my ears at least, to use the speaker level inputs.
Craig,
After I posted this I called Cambridge Soundworks, and they indicated that even though a full signal is flowing through the mains, the power from the amp of the receiver is only being used to power what the front satellites are using (100 Hz and up). The signal that the sub is taking (100Hz and down) is not being powered by the receiver at all and not sucking up power. The powered sub would handle that. I know not to always believe what manufacturers say, so I put it back to you. Does this make sense, or do you still think that the receiver is working extra hard with this setup vs. a linelevel setup.
Greg