Music Hall Turntable Hum?

Is it possible that you have placed the turntable or the IC's from it to the phono stage near a transformer in an amp or pre-amp or even a DDP. Try moving the TT to another location and see what happens. You might also check to see if the ground wire from the TT is grounded properly. If you think it is, then disconnect the ground and see what happens.

Well, I don't know when the hum becomes audible relatively speaking, but it strikes me that it might also be nothing more than the noise floor of the phono stage interacting with a cartridge with low enuf gain to cause you to crank it up to get sufficient volume. And, perhaps the more obvious, you are initially hearing the onset of feedback caused by excessive volume as a low level hum. Deep bass creates a lot of air movement, some of it subsonic, and that could be causing the TT/Arm/cartridge to resonate. Check this out by listening for hum increase when the stylus is not in the groove and see if the hum increases with volume.

Hope that helps a bit. Solving problems long distance is a bitch. :-)

Sounds to me like your problem is that your cartridge does not have high enuf output for your phono stage. What is the cartridges output? How much gain does your phono stage have? Your complaint reminds me of someone running a MC cartridge into a MM phono stage.