Can I rig a home theater amp to run in wall speakers?

My friend has an older rotel 5 channel power amp that he used to use with a rotel home theater preamp for a home theater.  Now he has a modern marantz home theater receiver that handles the home theater.  His new house has 8 in wall speakers distributed throughout the house.  He has a sonance speaker distribution box.  I advised him to use the rotel power amp to drive the speakers in the sonance box, using the pre-outs from the Marantz.  The current set up can only make use of 2 channels, due to the 2 pre-outs from the marantz, and thus, 3 of the channels in the Rotel power amp are going unused.  I'd prefer to put one pair of in walls at least on its own channels in the rotel, and minimize the quantity of speakers in the sonance box.

any thoughts?

Thanks Mark, and I have taken a look at the manual. Hopefully I can clarify some of the info provided by "dtc".

Zone 2 - When using Zone 2 speaker output, 7.1 is not an option for HT, however when only using Zone 2 pre-outs, you can do 7.1 HT. These Zone 2 pre-outs can drive 2 channels of the Rotel amp, but not directly. A passive VC will need to be inserted between the Zone 2 pre-outs and the Rotel amp. The manual implies that the Zone 2 pre-out is a fixed output, so depending on its level, it could overdrive the amp. It is true that Zone 2 will only play sources from analog inputs or the tuner. Any sources from HDMI or digital inputs are not available for Zone 2.

Using the stereo (L&R) preout - I believe this is the current setup. It will be necessary to select stereo only on the SR5006, no surround. Then the main VC will affect the volume of all speakers. "Is there a way to disable the speakers on the Marantz HT Receiver while the pre-outs send signal to the other speakers?" Yes, assuming there are no speakers connected to the speaker B outputs. The "Speaker A/B" switch on the remote will toggle, (A) - (B) - (A+B), then back to A. Set this to "B", then the HT main speakers will not play. Since stereo only was selected on the receiver, center and surrounds will not be playing as well. Also, if stereo only is not selected, these preouts will only output the L&R of a 5.1 signal, and likely sound poor on the in-wall speakers .

Trying to use more than 2 channels of the Rotel amp - possible, but a few ways to do this. Rather than list all the scenarios, is it possible to get a little info on what sources are used for the distributed audio, analog, digital, or both? For example, 2 channels in addition to how things are currently setup could be driven from Zone 2 pre-outs as described above, but those speakers would only play an analog source. RCA splitters could also be used, but depending on the arrangement, additional devices may be necessary. 

If, in fact, one of the speakers is truly mono, then you might want to think about making everything mono.    Wall and ceiling speakers and outdoor speakers seldom benefit from being stereo and mono is often better since there is seldom a "sweet spot". You can do this with simple Y cables - not elegant and I would not do it for critical listening, but it is often a good option for whole house music.
Thanks guys.  The source is an Apple TV via HDMI to the Marantz.  The Apple TV serves up a large collection of music on hard drive.  My friend is not an audiophile, he just likes music.  He is not even a gear enthusiast, nor one to obsess over the quality.  Of course, he appreciates nice sound, but there you have it.

TLS49, I think we are on the right track with the stereo output, taking advantage of the HDMI input on the Marantz.  So, he chooses stereo mode, sets the speakers to speakers B only, and his in-wall system is doing its job.  Sounds great.  

This is a relatively temporary band aid situation.  I think a stack of Sonos Connect Amps (or similar) would serve him better, but this solution may remain for a while, so we'd like to get the most out of it.

I really like the idea of using all 5 amp channels on the Rotel.  It just makes sense to have a speaker than can get its own 100 watt channel to take advantage of that, as well as to reduce the load and loss on the sonance box.  I think the outdoor pair can get 2 Rotel channels, perhaps the kitchen gets one (in mono?) and the sonance box gets a pair, now with only 2 pairs of speakers, reducing the load!

What do you think of this product?

How do we get the kitchen in mono?  One of these?

Ah heck.  I just realized there is a flaw in that plan.  He'd need to be able to turn off the outdoor speakers.  Cant be jamming in the living room, not using the outside area, and pissing off the neighbors.

Ok, please advise.


dtc, I agree with the idea of a mono due to no "sweet spot", however, IMHO, I would not just use a simple "Y" cable on the L&R pre-outs of the SR5006, main or Zone 2. This just shorts the 2 channels together, and may cause adverse effects. It would be best to use some type of a stereo to mono converter, even something as simple as a "Y" with resistors inline on the signal connections.

Here is an option that is very simple to use 4 channels of the Rotel.

(Example only, quality should be same as interconnects used.) Use this type of Y adapter on each (L&R) of the SR5006’s main pre-outs.

This gives you 2 pair of stereo RCA outputs with a female connection. That way, you can use normal interconnects for everything. (The splitter box from the link in your post would work also, just using 2 of its 4 outputs.) Use one of the pairs for 2 channels on the Rotel to the SS6 like the current setup. Then connect the other pair to the input of a passive volume control,

cheap passive VC -

better passive VC - only one input would be used

with the passive VC output driving 2 more channels of the Rotel to the outdoor speakers. Indoor speakers will play as they do now, but outdoor speakers will be able to play louder due to the increase in available power not being connected to the SS6. The main volume on the SR5006 will still affect all speakers, but the passive VC on the outdoor speakers can be turned down or completely off allowing a desired volume inside. Keep in mind that the passive VC only attenuates, so maximum volume of outdoors will still be determined by the SR5006 volume control. No doubt the outdoor speakers will be able to play as loud or louder than they do now with a given indoor volume, but more important, this solves the problem to turn outdoor down or off.

Now to try and use that 5th channel on the Rotel gets a little more complex. You would need the splitter box from your link, 2 passive VC’s, and a stereo to mono converter like this,

I do not advise using a simple Y adapter to convert stereo to mono. See previous post.

I would definitely use 4 channels of the Rotel as this creates more flexibility between indoor and outdoor speakers, but not sure about trying to use that 5th channel. Is there a major problem with volumes between the indoor speakers? Something too loud, not loud enough? And if so, what?