Please skip to post #5 for updated details So it seems my amp is making this "whine" noise and somehow only this one bass is amplifying it when in active mode and only when the bass volume is up to 98-100%. I attached a file so you can hear as I turn the bass volume up and down and step on the cable which reduces the level of the noise. Details: I just got a bass that has a Delano active/ passive preamp system. When in active mode I hear a high pitched whine only when the bass volume is at 98-100% range. If I back it off a hair it goes away completely, almost like the volume pot switches the noise on and off. In passive mode it doesn't do it, with other basses it doesn't do it. While experimenting I found that my amp is actually making this noise. With no cable plugged in the noise is only present when I turn the master volume on the amp to 0 or up to 100% range. On 0 it's very faint so I never noticed it. At 100% it's quite loud, and in between 0 - 100% it goes away. I have tried a Hum X and ground lift adapter but it's always the same. With this bass connected it doesn't matter what the amp volume is, if I turn the bass volume to 98-100% I hear the same noise but much louder than from the amp alone. Below 98% the noise is gone completely; it just cuts off. If I step on the cable while the noise is audible it changes the level (gets quieter), and if I get closer to the amp it gets even quieter. I have tried different cables too. This sound does come through the DI of the amp to the PA only when the bass is connected. With the amp alone or with other basses connected the noise does not come through the DI I assumed it could be a grounding issue so I checked all the grounds inside the bass and all is well, but there is no shielding of any kind. When I connect this same bass to 3 other guitar amps I have it doesn't have any issue. I have another bass with active system and it doesn't do this with the same amp, and my friends play their basses here twice a week and this has never happened. At least 5 different basses get played through this amp each week. ( I play drums too) I'm wondering if the push pull volume pot could be bad, or the onboard preamp has an issue, except that this bass works fine through 3 other amps I have. I know the source of the noise is the bass amp, but why is it only this bass magnifies the noise greatly and only when the bass volume is all the way up? What could it be?