does it have dual inputs of any kind? RCAs? If so, get some XLR-RCA adaptors (BAT makes a very high quality one) and use those to convert to RCA out of the (pre)amp into the REL.... ?
Karl- I JUST bought a Pass Labs X-250 to go with Martin Logan speakers and an REL Storm series 1 sub. It replaced a Bryston 4B-ST. The Pass is a fully-balanced, differential amp as is yours, connected via XLR Shunyata Aries interconnects from my Anthem preamp. The Storm is far more limited in it's input & adjustments then your Stentor, which may mean another upgrade is on the way (a Stadium III, maybe)!
Anyway, I started to get a bad ground hum from the REL when it is connected to the Pass via high-level Speakon connection in the 'traditional' setup method in the manual. It was most noticeable with the amp in standby mode. Connected in this manner is supposedly very bad for the amplifier inside the sub. This, of course, does not apply to the line-level LFE input.
I talked to Jim at Sumiko, who said to move the Speakon connector to the Hi-level BALANCED input, but ONLY connect the red & yellow wires to the positive speaker connectors. The black wire then attaches to a good chassis ground on the amp - not the right channel negative as normal. This will put it back into summing mode - I Think - I haven't had enough time to get my system back together completely yet to test it fully with the new amp.
Did they mention or have you tried that combination?
Hope this helps & Good luck.
Thanks for the suggestions. I tried using the Ayre's RCA and XLR grounds as suggested by several people including Sumiko, but to no avail (hum from the REL). I've escaped without damage so far, but don't want to keep messing around until I blow something up. From talking with Sumiko, it sounds as though there were circuitry problems getting the separate stereo inputs to sum properly, which is why they're not on the production units. And the REL only has a mono RCA input, so no dice there either. Maybe this will be solved on the MkIV...
An update on my Pass x-250 & REL situation-
I tried the balanced input on the Storm to no avail. Connected as Sumiko recommended, there is hardly any low-level output from the sub at all. I have to assume from this that the Pass is not a differential amp??
However, reconnected in the standard Hi-level Speakon input with the cables setup as I described (black to chassis ground) seemed to do the trick. I am going to call Sumiko back to verify, but this at least outputs levels that I thought it should.
I still have some fiddling to do - I also upgraded my Anthem AVM-20 to version 2.08 with the new DSP chip, and I am not sure where the biggest changes in sub operation came from - the new amp or the new programming. (I know - I made too many changes at once....)
Quick question. It's almost impossible to get help on my stentor III. I have some burned resistors r8 and R13... can anybody look at there sub amp and let me know what the values are?
They (rel) only work through dealers and distributors and want to replacethe unit for almost the cost of a new one... can anybody help, either by looking at theres and letting me know whatthey are or direct me to someone or a shop.