As I understand it, using subs for stereo requires TWO -- one for each of the two channels and here is a quote from Ron Cornelius at McIntosh (knows his stuff but often is extremely brief due to his time constraints on either of the two McIntosh forums and his many duties at McIntosh). I started a couple of threads on how to utilize two subs in stereo mode as well as HT mode and among the responses is this one from Ron C: (hope it helps)

You might visit the following link and do a search -- think you can visit and search without being a member:

http://www.audioaficionado.org/mcintosh-audio/

MikeSp

Yes you can use aux 1 and 2 as your left right sub outputs. If you set the sub/Front size to XXLthen these will produce LFE information. If you are using another mono sub in the sub out you can leave the LFE there. Whatever you cross the surround speakers at will be the cut off frequency for your sub output as this is where the bass will need to come from.
Cross everything over 4th order L-R and Room Perfect will balance the system.

I actually have my own system set up this way with stereo bi-amp fronts cutoff at 40Hz and a big sub cut off at 100 Hz on top and all the way to 20Hz on the bottom. This allows my small surrounds to have their base from the single sub.

As I understand it, using subs for stereo requires TWO -- one for each of the two channels and here is a quote from Ron Cornelius at McIntosh (knows his stuff but often is extremely brief due to his time constraints on either of the two McIntosh forums and his many duties at McIntosh). I started a couple of threads on how to utilize two subs in stereo mode as well as HT mode and among the responses is this one from Ron C: (hope it helps)

You might visit the following link and do a search -- think you can visit and search without being a member:

http://www.audioaficionado.org/mcintosh-audio/

MikeSp

Yes you can use aux 1 and 2 as your left right sub outputs. If you set the sub/Front size to XXLthen these will produce LFE information. If you are using another mono sub in the sub out you can leave the LFE there. Whatever you cross the surround speakers at will be the cut off frequency for your sub output as this is where the bass will need to come from.
Cross everything over 4th order L-R and Room Perfect will balance the system.

I actually have my own system set up this way with stereo bi-amp fronts cutoff at 40Hz and a big sub cut off at 100 Hz on top and all the way to 20Hz on the bottom. This allows my small surrounds to have their base from the single sub.

Thanks, that is helpful. Unfortunately, it may be a bit before I am in a dedicated HT room and have the space for a second sub.

One other question I have come across involves the remote triggers. I am trying to utilize the setting for leaving the remote triggers on for an additional amount of time, but no matter how I set them up, the additional time only works if I switch between sources. When I turn the unit off, the triggers go off with it. Am I missing something? Thanks in advance everyone.

I spoke with Chuck and it turns out the triggers all go dead when the unit goes into standby mode so there is no way around that.

I also spoke with him about the sub setup and he said that the McSUB setting that was available on previous models is not on the 150. I have been playing with the crossovers and I think I will be able to get closer to what I want with some changes.

Chuck mentioned using the natural roll off setting on yes, can anyone explain to me what that setting does? Thanks in advance.

Chuck mentioned using the natural roll off setting on yes, can anyone explain to me what that setting does? Thanks in advance.

I believe that it means that the crossover does not cut off 100% at whatever you have it set at. For example, IF you are crossing over your mains at 80 Hz and the subs handle everything below that, it does not cut everything below 80 Hz off but is somewhat graduated below 80Hz with the bulk of the cutoff at 80.

Somebody correct me if incorrect.

MikeSp

I believe that it means that the crossover does not cut off 100% at whatever you have it set at. For example, IF you are crossing over your mains at 80 Hz and the subs handle everything below that, it does not cut everything below 80 Hz off but is somewhat graduated below 80Hz with the bulk of the cutoff at 80.

Somebody correct me if incorrect.

MikeSp

I spoke with Chuck again and he informed me that the natural roll off is similar to the McBASS setting from older models. It basically sets the output to that speaker to full range, but also sends the signal below whatever you crossover at to the sub.