Jeff Rowland with Rel sub

When connecting a REL to a differential amp using the high level input (the best choice for 2 channel music) you must ground one of the positive wires of the the supplied Neutrix connector to the amplifier. I believe the configuration is red positive to ground, yellow positive to positive amplifier speaker terminal and black to the negative amplifier speaker terminal for the same chanel (either left or right) you have chosen to connect the positive lead to. Double check the configuration; it should be in the owner's manual. Not sure if the Rowland is a differential, but I hope this info can help aleviate problems people may have hooking up their RELs

Its not clear to me how you're connecting, but I'll comment on what works for me...

With my Ayre V-5x (balanced differential), I use the high-level unbalanced input on the REL. I connect the yellow wire to Left+, the red wire to Right+, and the black wire to a chassis ground screw on the amp.

How are you connecting?

I connected according to the directions in the owner's manual: FIG 2 unbalanced high level input at the sub. To the amp: red to right positive, black to right negative and yellow to left positive. Todster, I tried your suggestion and got nothing.

I am currently using the Concerto Int. with a REL B-3 sub connected via the Neutrix interconnect. Fabulous results.

I had the same problem with my JRDG 201 monos. The fix was simple, you have to lift the grounds on the Rowland. Use a cheater plug on the AC chord. I also have to disconnect my HT processor to the RCA input on the sub when listening to 2-channel. Of course, I'm using the Neutrix connection to speaker out on the amps for 2-channel music listening.