I managed to get a sound level meter from radio shack and calibrated all my speakers to 75db. Actually my whole system sounds better , but god damn, reference levels are loud!
As for my RC-3, there's still no change in the tone. I tried everything you guys suggested and I don't think it's defective. I think the problem might be the location of the speaker. It's in a kind of cabinet so i think the speaker might be vibrating it at higher levels.
Thanks for the tips!