I have a Sony STR-AV910 receiver hooked up to Technic's A30 speaker towers. I've got a computer, record player, CD player, and tape player hooked up to the thing. About 4 months ago I noticed that a loud hum/buzz thing was coming from the speakers, particularly the sound blasters connected to the surround sound ports. The buzz was completely independent of the volume control. I didn't try to fix the problem myself, just took it to be repaired. After that, and $80, it seemed fixed. The humming stopped. The receipt says they cleaned and burnished the surround sound ports. For the most part, the problem was fixed. There still was a slight hum, but it was basically silent. Now about a week ago, I noticed the hum came back. Again, it is completely independent of the volume control. I tried isolating any of the inputs, and that wasn't the case. I tried swapping out speakers, and all speakers basically emitted the same exact tone. I would have thought it was the computer, but I tried plugging it in on the opposite side of the house with the computer unplugged and that didn't work. I thought maybe it was the cheap-o sound blasters, but that didn't do anything either. Perhaps it was the old record player. Nope. I can not figure out what this is, i thought maybe it had something to do with the electrical wiring in the house but that isn't the case. So I am guessing it has something to do with the amplifier. What could the problem be? And how could I possibly fix it?
Thanks so much!