rel with monoblocks

This means that if you loose the stereo performance of the speakers as the hook-up combines the two channels. It is amazing how many systems I have seen with Rel's where the owners have done this and do not know it is occuring.

This is the case with the hook-up instruactions immediately above (SMW1950) has the same signal now going to both speakers (whatever signal is just supposed to go to the left speaker has now been mingled with the signal to the right speaker and this combined signal is going to both speakers). So in actuality, he is running a pair of mono speakers with a sound stage that is always centered (outside of the impact of the subwoofer being off-center).

This is simply incorrect. With the red wire connected to the Right amp + post, Yellow to the Left amp + post, and black connected to either L or R - post (or any other ground point in the system) it's not possible to combine L and R channels in your amp. I have mine connected this way and am positive I have not lost stereo out put from my speakers.

One qualification: Fully balanced amps can't necessarily be connected this way.

Bdgregory, I have hooked it up exactly as you have suggested, both with two mono amps and with dual mono/dual differntial stereo amps and the end result has been the same for me every single time - that is crossed channels (ie. left signal also going to right speaker and vice versa).

The mono amps that this has occured with were BAT VK 60s run as mono amps and Channel Island mono amps. The dual differential amps have been Krell FPB 200, FPB 300C and Levinson 331.6 with all of the above (except possibly the CI amps) running in balanced mode. I have the Storm 3.

In all of these cases I ended up just connecting the sub to either the right channel or right amp. This corresponds exactly with what I was told on the telephone during two separate conversations with the Rel distributor (Sumiko I think, but am no longer 100% sure on the distributor name).

ok, I understand. Indeed not all amps are the same. I knew fully balanced amps present issues for the Rel (and not all fully balanced amps are the same), and it's apparent your amps do likewise. My amps are mod'd B&K M200's and I have no issues with them. Same for CJ's I ran previously, and the Ayre V3 (which is a fully balanced amp but only required a different ground arrangement) worked fine as well.

Bdgregory, I had no problem with my Rel and my B&K 507 S2 or with my CJ 5-channel amp.

I think the Rel's are great Subs (regardless of price comparisons to others) and can most highy recommend them. It was disconerning to me when I would run into troubles with them crossing the channels. If not for the conversations with Sumiko?/Rel, I would have assumed it was my sub.

I am currently running stereo (non-dual differential) and with terrific results. Thanks for your advise as well as I know you are an experience and knowledgable Agoner and would encourage other readers to take your advice, but at the same time watch or test for cross-channel experiences as I have encountered. You may be 100% correct in that it may be amp dependent. I appreciate your replies so that other readers can get further information and understanding from two different people's experiences.

Has there been anything new on this  topic since 2010? I'm hoping to add an REL-328 to my current system which is running two (one for right channel and one for left channel) Marantz MA-500 monoblock amplifiers. Will a connection as described by ckoffend above work? Is there a possibility of causing damage to the amplifiers?
Thanks