Speaker hiss from sub

Have you tried the high-level inputs from the speaker outputs on the amp instead?

Does the hiss continue when you unplug the subs, leaving only the AC cord connected?

Hiss goes away when I unplug the power for the subs but have them connected to the amps. It also goes away if the subs are powered but they are unplugged from the amp.

I'm trying to understand something.  Is the hiss coming from the main speakers or the subs?

From the main speakers 

Not sure if this applies to you but I've had problems with my Rel subs..Rel replace one  of them about 6 months in and now the replacement is doing the same thing..I called a Rel dealer and was told they were having lots of complaints and several returns.. Rel is having build issues from whst I'm told...

Okay, thanks. I reach out to REL.

Have you tried running an RCA cable from the .1/LFE to an unused RCA jack on your amp? If of course your sub has HT .1/LFE .

I haven’t, I’ve only run the Neutrik cables that came with the sub—I don’t have RCAs that will go far enough. I have wonder if running RCA from the pre would help but part of the advantage, theoretically, is to run directly from the amps.

I have emailed Music Direct to see if they have any ideas.

R. Edmund Lord marketed a sub bass speaker to accommodate people using receivers lacking preamplifier outputs and / or small low frequency restricted speakers. Along with RCA inputs he included speaker / high level inputs as do many manufactures. 

Using the more widely used preamplifier outputs directly to the subs low level inputs bypasses any noise, frequency restrictions and distortion imposed by the speaker amplifier and its input and output stages. As with any sub you determine any audible advantage. 

Monoprice or Blue Jeans cable offer economical custom length RCA or XLR terminated interconnects. 

Solved for $2.89! On a suggestion from Music Direct I got two “cheater plugs” from the hardware store—hiss gone!

Hiss or hum?