Question: Just acquired a monoblock amp (Marantz MA500) in hopes of running a center speaker with my soon-come RR 2150. The RR 2150 manual says I need "Y" interconnects in order to hook an external amplifier up to the receiver's pre-outs/main-ins. Not sure how all this works, so I'm just wondering what to buy. Do I need two of Outlaw's Y-Adaptors and one set of PCA interconnects?

I'm not sure how you are setting this up. The RR2150 is a purely stereo receiver, with no center channel output. Are you thinking of summing the left and right channels to produce a center signal?

That's kinda what I was thinking—merging the left and right. Is that not possible?

If you use on ‘Y’ adapter between the left channel pre-out and main in, another ‘Y’ adapter between the right channel pre-out and main in, and a third ‘Y’ adapter to combine the R & L for a mono mix to the mono amp, the L & R main inputs will also carry that same mono mix to the R & L amplifiers inside the RR2150. This would result in three channels of mono, no stereo anywhere.

Your other options (maybe): a ‘Y’ connector on an unused output pair such as those meant for an external tape recorder or an external effects processor. The external processor outputs will only work for a ‘mono mix’ if the outputs are active while the External Loop Select button is ‘off’ because you cannot return the mono mix to the external processor inputs unless you want the same problem as with the pre-outs & main ins. The problem with this is that the volume control on the RR2150 will not affect your mono mix. That volume would have to be adjusted manually.

Another option: if you could get a hold of a couple attenuators meant to reduce a loudspeaker level signal to a line level signal, you could put one attenuator in parallel with the L speaker output, one attenuator in parallel with the R speaker output, the put a 'Y' adapter on the output of the attenuators. This would persevere both a stereo signal for your normal R/L speakers and have the mono mix signal follow the volume of the R/L speakers. The only (minor) issue here is that the center channel may not be as free from hiss, noise and distortion as one generated purely from internal or line level signals.

Last but not least, RS used to, and may still, carry a small RCA-connector distribution amplifier, one set of inputs, and three or four sets of outputs. You use one of these on the pre-out, main in connections with one pair of outputs joined by a 'Y' connector. If the RS unit is a true distribution amplifier, the L/R signals going back to the main inputs will still be separate stereo signals. Any imperfections placed in the signal path by this DA will become a part of your sound, but may be negligible.

Thanx for the info, bb4tb. I thought it might be as simple as running the main speakers from the RR 2150's designated left and right channels, and hooking a third speaker to the monoblock. Hypothetically, what would happen if I did that? Would that interfere with the stereo sound?

Ahhh, I get it now. Just did some more research and took a look at the RR 2150 manual, and it seems that bb4tb's first ("maybe") option is suggested there, although not specifically for a "mono mix." Instructive nonetheless. It'll be a bit easier to figure all this out once I get the components in my living room. We'll see...thanx again. Outlaws rock!