I've noticed that I have a pretty bad low end hum going on with my TV on Windows 7. I have a Saturn STB feeding my HTPC through SVideo and connected to a Hauppauge PVR150. The TV is playing really bassy, and when you change channels it sounds almost like the speaker cables do when they touch metal.
This same setup worked perfectly in Vista. I've also changed the audio Left/Right RCAs from the STB to the PVR150 but the same thing happens.
I don't have any issues with sound in DVD/Videos/Music - Only Live and Recorded TV.
I have tried tinkering with any sound settings I can find in Windows and also in Media Center - nothing makes a difference.
The STB is not turned up too loud which is what I initially thought, it's only on half volume - and i still get the hum even if I have Windows 7 turned way down.
I've even turned my sub down to 0 manually and I still get the humming.
Any help on this would be greatly appreciated, if not for my sake then for the guy who lives beneath me :)