Question on REL Storm

I recently purchase a used Storm off Audiogon. I am still making adjustments for integration with my B&W Sig 805's and I do like how the sub fills out the sound. I have it hooked up to the speaker connections on my BAT VK-200 amp and also to the LFE out on my ht processor. While it all sounds good, when it sits at an idle or everything is off but the amp(I leave the amp on all the time) there is a hum coming out of the sub. This will get softer or louder with the volume control. If I turn the amp off it goes away. Is this normal, or do I have a another problem with grounding or other connections?
Doesn't sound like a ground issue to me. When my REL isn't grounded, it hums steadily all the time, whether the amp is on or off and independent of the volume control. I don't know what the answer is, but it doesn't sound like ground issues to me.

Good luck,

I would try removing the RCA connection at the back of the REL that leads to the HT Processor while leaving the High Level Neutrik speaker connection to the BAT amp. (I'm assuming the BAT amp gets its signal from the HT Processor and the BAT feeds the right and left main speakers). Listen to 2 channel music and see if the hum goes away; if it does you probably are experiencing a ground loop problem.