E15 Hum issue

I'm getting a hum in one of my E15's. Both are hooked up the same. I've checked all connections and everything is secure. I have two connections, as follows:
1. Rogue RP5 --> dSpeaker 8033SII --> E15 Line In
2. AVM70 --> miniDSP Flex --> E15 LFE In.

I disconnected the cables at the intermediate (dSpeaker & miniDSP) and the hum persists.
I disconnected both at the E15 amp and the hum went away. I can plug either one back in (eg feeding LFE or feeding Line In) and the hum comes back.

Any suggestions? Amp going out? Possibly two bad cables?

I then disconnected the problem sub and hooked an old CD player directly to the Line In on the sub. Played some music (bass ;-)) and no hum that I could tell.

Over the next day or so, I'll try swapping sub cables to see if the hum moves from one sub to the other. Will likely also try disconnecting everything and hooking back up one at a time to see if/when the hum is (re)introduced.

I also emailed Rythmik via their website contact form to see what they suggest.

In the interim, wondering if Dave or anyone on the Ascend forum has any suggestions.

Well, the hum issue seems to be resolved. I ran the sub volume knob up/down a few times and, viola, no more hum. Did hear back from Enrico at Rythmik indicating it was a ground loop hum. Let Rythmik know what I did to resolve the issue. If they provide any further feedback, I'll post here for reference in case someone else has a similar issue in the future.

Hmmm. That is interesting.

I am glad it is resolved, but to me, that seems like an amp issue.

I worry as I have had my F15HP since they were first announced and wonder about the longevity of the amp. Of course, I probably just jinxed myself.

I hope you didn't jinx yourself!
I'll see if Rythmik has anything else to say.