A few days ago my sub started making a very loud hum. Actually, its a hum that starts low in volume and steadily increases until I shut it off. ARV and connections are good. Is this a bad amp? Thanks for any help.

very likely. Try unpowering / unplugging the sub and then remove the connection from the AVR / Pre Pro. Then plug the sub back in. If the same thing happens then it is very likely your plate amp on the sub. Give the manufacturer a call regardless.

Thanks for the response. Tried what you suggested with no luck. This thing is about 13 years old. I replaced the driver about 2 years ago so I guess now it is time for a new amp. The DAYTON SA240 would fit in the existing cutout nicely and it has about double the power of the old one. Anyone have experience with this amp?