Can I connect a 2nd receiver to a pre-out?

[StJimmy86]

I recently got interested in real home audio instead of the “home theatre in a box” approach of soundbars, and having a lot of fun with it. I can see why audio people aren’t real fond of soundbars. I’m using a Denon ACR-X3700H receiver and have created a 9.2 system which sounds great. The receiver has processing for 11 channels though with an external amplifier. I got a Niles SI-2100 amplifier to run the Height2 pre-out channels but have had problems with it buzzing (no it’s not a ground loop problem; I used an isolator and it didn't solve it), so I used an RCA-to-3.5mm aux jack to connect the Height2 pre-outs from the Denon into a powered soundbar, thinking to use its internal amplifier to see if the same issue occurred and it sounds great, so I intend to return the amplifier.

This got me thinking though, if I can use a soundbar as the amplifier for the Height2 pre-outs, why not a 2nd receiver? That’s where I’m at. I’m thinking if I get a 2nd receiver, maybe something like an AVR-S650H, and I connect the RCA Height2 pre-outs from the “main” receiver to the RCA aux inputs on the “auxiliary” receiver, I could create a “system within the system” devoted strictly to height effects by connecting passive speakers to the 2nd receiver's amplified outputs. I’m looking at the setup and I don’t see why this wouldn’t work; the pre-out from the “main” receiver is obviously not amplified so I don’t see how it could damage the 2nd receiver, and the 2nd receiver is going out to passive speakers so nothing’s going back to the first. It seems to make sense, but something just seems “wrong” about daisy-chaining receivers together.

So, my question is, am I missing something, or is it OK to use a 2nd receiver as the external amplifier for a receiver’s pre-out? I'm sorry in advance if this is a dumb question.

 

[Eppie]

Not recommended at all for me. All you need for the heights is 2 channels of amplification, nothing more. All of the other amplifiers, processors, inputs, etc. would be unused and wasted. Yes, in theory it would work because the height pre-out is line level and can drive any line level input on the 2nd receiver, but it seems like a big waste of resources and money. All you're using it for is 2 channels of amplification any way. Best to stick with a 2-channel amp and resolve any grounding issues. While the isolator did not solve your issue, there may have been other things you could have tried. Don't assume that it is not a ground loop after trying one thing. There are members here that can recommend a step by step process to try and isolate where the buzz is originating from.

 

[Pogre]

Agree with Eppie. Just get a regular power amp with at least 2 channels. You have a great avr with a full set of preouts. There's no need for a 2nd, lower tier receiver.

 

[StJimmy86]

Awesome thank you for the input!

I suppose on a side note, is there any reason why the pre-out would have all kinds of buzzing problems when connected via RCA to a 2-channel amplifier, but when connected to a powered soundbar or other powered speakers (I've tried 4 and all worked fine, crystal clear) via a 3.5mm jack off an RCA adapter it works? My assumption would be that if it were a ground problem, I shouldn't be able to resolve it just by adapting the RCAs to a 3.5mm jack.

 

[lovinthehd]

I'd suspect the problem is with the Niles amp rather than your avr's pre-outs. While you can use another receiver as just an amp I'd think you could do better with a power amp. Maybe consider a power amp for your mains and let your avr handle the surrounds....

 

[Eppie]

I'd suspect the problem is with the Niles amp rather than your avr's pre-outs. While you can use another receiver as just an amp I'd think you could do better with a power amp. Maybe consider a power amp for your mains and let your avr handle the surrounds....

I believe that the height channel only gets routed to the pre-outs; no option to re-assign the main L/R amps to the height channel and use a separate amp for the main L/R. Would have to check the manual to confirm.

The buzz may be present on other devices but they have less power than the Niles so not noticeable. More likely that it's the Niles though, as mentioned above. First thing usually is to swap the RCA cable for any other and also try an AC plug adapter that lifts the ground pin (3 prong to 2 prong). What happens when you disconnect one end of the RCA cable? Any difference if you disconnect the RCA from the Denon or from the Niles? You can also run a single strand of wire from the Denon's signal ground terminal to the Niles (you can use a chasis screw or slide it under the RCA ground connection for testing).

 

[StJimmy86]

I believe that the height channel only gets routed to the pre-outs; no option to re-assign the main L/R amps to the height channel and use a separate amp for the main L/R. Would have to check the manual to confirm.

The buzz may be present on other devices but they have less power than the Niles so not noticeable. More likely that it's the Niles though, as mentioned above. First thing usually is to swap the RCA cable for any other and also try an AC plug adapter that lifts the ground pin (3 prong to 2 prong). What happens when you disconnect one end of the RCA cable? Any difference if you disconnect the RCA from the Denon or from the Niles? You can also run a single strand of wire from the Denon's signal ground terminal to the Niles (you can use a chasis screw or slide it under the RCA ground connection for testing).

I had attempted to swap RCA cables at the start; in addition to both RCA cables having the same problem in this system, they both work perfectly with known-good components so I ruled out an RCA cable issue. I don't think it's an issue with power levels because when I use a 330W Polk soundbar connected via the 3.5mm jack and turn it up all the way the sound is crystal clear, whereas the Niles is a 2 x 100W amp and buzzes at any volume. When the isolator had failed to rectify the issue I did attempt to connect the components' metal bodies together (the Denon has a very convenient signal ground terminal) and it had no effect. This is why I'm fairly confident that it's not a grounding issue; directly connecting the metal bodies of the two creates no change. This is why I'm intending to send the amplifier back to Crutchfield, even though they don't seem to think it could be bad.

That's what started me down the path of figuring out what else I can do with that pre-out. Frankly, I could just leave the Polk soundbar connected, it actually sounds decent. I just don't want to have to deal with mounting it above the TV. But it got my mind turning, and I was thinking that if I do go that route and replace it with the Nakamichi Shockwafe 9.2 system I was running back before I started the whole home theatre project and I set the Shockwafe to stereo mode, I could bring the Height2 pre-out signal through all channels. And if that's feasible, why not just a whole other system? It seemed like a kind of wacky idea though so I wanted to get the opinion of some folks with more experience

Thank you to everyone responding for the insight, much appreciated!

 

[GranteedEV]

This got me thinking though, if I can use a soundbar as the amplifier for the Height2 pre-outs, why not a 2nd receiver?

Pre-amplifier outputs tend to run very hot in terms of voltage in order to sent a very strong and clean signal to the amplifier (so that the gains don't need to be cranked up to noisy levels), whereas typical RCA interconnects do not run very hot (so that they can be, well, preamplified at the following stage).

 

[Eppie]

I had attempted to swap RCA cables at the start; in addition to both RCA cables having the same problem in this system, they both work perfectly with known-good components so I ruled out an RCA cable issue. I don't think it's an issue with power levels because when I use a 330W Polk soundbar connected via the 3.5mm jack and turn it up all the way the sound is crystal clear, whereas the Niles is a 2 x 100W amp and buzzes at any volume. When the isolator had failed to rectify the issue I did attempt to connect the components' metal bodies together (the Denon has a very convenient signal ground terminal) and it had no effect. This is why I'm fairly confident that it's not a grounding issue; directly connecting the metal bodies of the two creates no change. This is why I'm intending to send the amplifier back to Crutchfield, even though they don't seem to think it could be bad.

That's what started me down the path of figuring out what else I can do with that pre-out. Frankly, I could just leave the Polk soundbar connected, it actually sounds decent. I just don't want to have to deal with mounting it above the TV. But it got my mind turning, and I was thinking that if I do go that route and replace it with the Nakamichi Shockwafe 9.2 system I was running back before I started the whole home theatre project and I set the Shockwafe to stereo mode, I could bring the Height2 pre-out signal through all channels. And if that's feasible, why not just a whole other system? It seemed like a kind of wacky idea though so I wanted to get the opinion of some folks with more experience

Thank you to everyone responding for the insight, much appreciated!

So the buzz is at the same level on the Niles regardless of where the volume is set on the Denon? Have you run the Niles without anything connected to the inputs or is the buzz there only when the RCA cable is attached? What if you connect the RCA cable to just the Niles but short out the other end? Your description does seem to point to the amp.

 

[lovinthehd]

Pre-amplifier outputs tend to run very hot in terms of voltage in order to sent a very strong and clean signal to the amplifier (so that the gains don't need to be cranked up to noisy levels), whereas typical RCA interconnects do not run very hot (so that they can be, well, preamplified at the following stage).

Are you talking about the differences between the variable output of a pre-out vs a line-level fixed output? Different things....

 

[GranteedEV]

Are you talking about the differences between the variable output of a pre-out vs a line-level fixed output? Different things....

Essentially, yeah. And since the former is variable, its peak voltages are considerably higher than a line level output would produce. Input stages aren't always built for that.

And the fact that they're different things is why I'm suggesting avoiding that scenario.
Not that I haven't ever done it but uh I do some things I don't recommend.

 

[StJimmy86]

So the buzz is at the same level on the Niles regardless of where the volume is set on the Denon? Have you run the Niles without anything connected to the inputs or is the buzz there only when the RCA cable is attached? What if you connect the RCA cable to just the Niles but short out the other end? Your description does seem to point to the amp.

The buzz is there even with nothing attached to the RCA inputs.

The one time I did make it work, however, I used a tablet's 3.5mm output jack into an RCA adapter to the Niles inputs, then the amplifier would work when a music track was playing, perfectly clear. However, if you pause the track, it goes back to buzzing. Which made me think that it requires a signal input in order to work, which is going to be a problem on height channels that may not have audio on the source mix all the time (helicopters can't always be flying overhead lol). However, when connected back via the same connection to the pre-out, it's back to causing problems, even though the same pre-out connections work fine with any other powered speaker with built-in amplifiers. That's what sent me down the rabbit hole of "I wonder what else I can connect to this pre-out..."

 

[Eppie]

The buzz is there even with nothing attached to the RCA inputs.

The one time I did make it work, however, I used a tablet's 3.5mm output jack into an RCA adapter to the Niles inputs, then the amplifier would work when a music track was playing, perfectly clear. However, if you pause the track, it goes back to buzzing. Which made me think that it requires a signal input in order to work, which is going to be a problem on height channels that may not have audio on the source mix all the time (helicopters can't always be flying overhead lol). However, when connected back via the same connection to the pre-out, it's back to causing problems, even though the same pre-out connections work fine with any other powered speaker with built-in amplifiers. That's what sent me down the rabbit hole of "I wonder what else I can connect to this pre-out..."

That's an odd problem and sounds like a design flaw in the Niles. If Crutchfield will take it back I would go with your original plan to return the amp and try a different make/model. A 2-channel amp is still the best solution with that Denon.

 

[Eppie]

That's what sent me down the rabbit hole of "I wonder what else I can connect to this pre-out..."

Thinking about this some more, there is one situation where your original idea would make sense, and that is the used market. There are a lot of old AVRs with no digital inputs that people are selling for cheap. You can use one of those just as an amplifier. Set the input source and the volume level and then the surround pre-out on the Denon would control the volume. This is the budget solution but the system will look odd with two AVRs instead of that nice slim amp.