How do I switch between 2 pre amps with 1 power amp??

Kructuan

Novice Member
Hi - I need some help with how to switch between two pre amps with one power amp.

I recently (unintentionally) acquired a Rotel RC-972 pre amp and RB-991 power amp. Fortunately my current set up includes a Yamaha AVR with a full set of pre outs so I thought I would just integrate the 2ch power amp for front my speakers and sell the pre amp. However after auditioning the pre and power amp together it is clear that would be a foolish thing to do.

This presents a problem because I need the Yamaha to be connected to the power amp for everyday family use with HT duties and music but on the (rare) occasion when I have some time to listen to music by myself I want to be able to easily switch to the rotel pre amp as the input to the power amp without having to reach behind and swap the cables round. The power amp has both unbalanced RCA input and balanced XLR input but the AVR and pre amp have only RCA outputs.

It seems my options are;

  1. Connect both RCA outputs from the AVR and pre amp to the unbalanced RCA input using a Y splitter of some kind. I can then either keep the AVR and pre amp both connected and only have one turned on at a time OR disconnect the one that is not in use. For me here the unknown is how the presence of a splitter will affect sound quality. How would either AVR or pre amp be affected with they are part of a signal chain which includes another pre amp? I guess the easiest and cheapest option is a corded y splitter (rather than a small solid item) that is easily reached.

  2. Connect both AVR and pre amp to a switch box. I almost bought a Schiit SYS but the shipping cost to New Zealand and along with the uncertainty of how it will fare with 1m RCA cables feeding to it and then another 1m on the output to the power amp, put me off. I have also considered a cheaper option from Amazon but I am not too keen on introducing a low quality item in my set up. I would love to hear from anyone out there who is using a SYS as a switch for two pre amps for one power amp.

  3. Use the XLR input of the power amp for one pre amp source and RCA for the other and switch between them without disconnecting anything. This is my ideal solution and there are many RCA to XLR cords available but there are seemingly many potential issues with this which I’m not knowledgeable enough to understand. I have a copy of the service manual for the power amp (model RB-991) which includes all schematics but I cannot decipher any of it.
All thoughts and advice on these three options are most welcome, in particular on the RCA/XLR and Schiit SYS.

However....I do have another option available to me. Just thinking about it gives me a headache. I have a Beresford speaker switch box currently going unused. It can switch between two amplifiers with one set of speakers and a while ago I would switch between my Marantz PM-66SE KI and the Yamaha and it worked perfectly. I could theoretically set up the Rotel pair as one amplifier input with the Yamaha as the other and have them drive my front speakers BUT I have a REL sub which I use with a Neutrik Speakon connection rather than LFE. I would also like to keep that connection available for both amplifiers via the Beresford switch. Do any TC-7220 owners out there have any experience with incorporating the high level Neutrik connection between two amplifiers and one set of front speakers?
 

Ugg10

Distinguished Member
Easiest was is to connect the AVR front L/R pre outs to one of the line in connection on the rotel preamp. The front speakers are then connected to the rotel power amp (which is connected to the rotel preamp).

For set up - set the preamp volume to say half way putting a mark on the volume knob/faceplate so you can return to that position easily and run your AVR set up to balance the front/centre/rear/sub.

So when you listen to AV select the input on the preamp the AVR is connected to and put the preamp volume know at the selected position and use the AVR for volume control. When listening to music use the preamp as normal with your selected source (connected to the preamp) but replace the volume know when finished for future AV listening.

This is a no cost option which you can try and see how you get on, if you cannot work this option then start to look for tech options.
 

Kructuan

Novice Member
That did occur to me but I discounted it because I assumed that the pre amp wouldn't deal very well with receiving a variable pre amp signal. Plus, adding the extra step in turning the whole everything on just creates another variable where one of my dear family members could do some damage - the RB-991 can pump out well over 200w per channel and my speakers are rated to only 120w and I can easily imagine volume nobs being turned to max before they realise the pre isn't on or is on the the wrong input. I'll still give it a try on the weekend though, thank you.
 

Mark.Yudkin

Distinguished Member
Solution 1 won't work (might cause some smoke though), and 3 isn't much better. The RC-972 doesn't have a processor mode, so oruting through it will require more courage than I could muster. A Beresford after the AVR / power amp will work fine, but performance will be better using the stereo L&R preouts of the Yamaha AVR to the Rotel power amp. For this you need a line level switch, but there is no need to import a Schiit SYS; a simple switch available locally will be fine. Either way, sharing the REL sub will always be an issue in such a setup, involving compromises.

You mention ease of operation. For that you would want an automatic switch (e.g. http://www.specsserver.com/CACHE/FRURYYHADNPL.PDF), but this option has its price.
 

Blupetros

Well-known Member
I do a similar thing as your option 3 although my pre-amp has Bal connections as well as RCA.
Use Balanced from pre to power when listening to music, switch power amp to unbalanced for AVR front L & R connection. Works a treat. I have never used XLR to RCA though, but don't see why it shouldn't work.
 

Barcoing Mad

Active Member
Make yourself an RCA socket panel or use a couple of three way light switches so you can select whichever input you want.
 

Rambles

Distinguished Member
I had a set-up similar to this, it worked fine, bit of a faff though, which is why I now have an Arcam AVR for both movies and music, bit easier. Anyway, here is what I suggest, along the lines of what has already been mentioned really...

AVR pre-outs into one input of the Rotel pre-amp, that is always used at a fixed volume for that input

Pre outs of the pre-amp into the power amp.

Main speakers connected to the power amp.

Sub connected to the power amp via high level inputs (I presume that's what you mean by the neutron connecter, that it is fed from speaker outputs of the amp)

All music sources connected to the remaining inputs of the Rotel pre-amp, which is when you will need to adjust the volume, but return it back to the same spot for the AVR input.

If you use the speaker switch, as well as adding another box, and a lot of additonal cabling, you will miss out on havng the benefit of the power amp when using the AVR.
 

BlueWizard

Distinguished Member
Here is a Photo of the back panel of the Rotel RB-991 -

https://img.usaudiomart.com/uploads/large/1064584-rotel-rb991-power-amplifier.jpg

Notice it has Balanced and Unbalanced inputs. If one of your Pre-Amps has Balanced out, you can likely feed one Pre-Amp to the the RCA and the other Pre-Amp to the XLR Balanced.

But it is generally bad policy to tie the OUTPUTS of two different devices together. There is a chance they will short each other out. You need some type of isolation between them. The Balanced and Unbalanced Line Ins would likely provide the isolation you need.

If that is not an option, then it become complicated, and will likely require some type of Switch or more hardware of some type.

A simply RCA Line Switch would allow you to switch between the Pre-Amps. These are usually purely passive devices, so they are not directional. A simple 2-way switch can be 2 In/1 Out, or it can be 1 In/2 Out. These are also not very expensive.

https://www.amazon.co.uk/s/ref=nb_s...=RCA+audio+Swtich&rh=i:aps,k:RCA+audio+Swtich

A simple rotary switch device assure that only one device can be on-line at a give time -

https://www.amazon.co.uk/HQ-3-Way-Stereo-Input-Control-black/dp/B000I8OOS8/

https://www.amazon.co.uk/s/ref=nb_s...r+Swtich&rh=i:aps,k:RCA+audio+selector+Swtich

That is probably the simplest solution to your problem.

Steve/bluewizard
 

Kructuan

Novice Member
Here is a Photo of the back panel of the Rotel RB-991 -

https://img.usaudiomart.com/uploads/large/1064584-rotel-rb991-power-amplifier.jpg

Notice it has Balanced and Unbalanced inputs. If one of your Pre-Amps has Balanced out, you can likely feed one Pre-Amp to the the RCA and the other Pre-Amp to the XLR Balanced.

But it is generally bad policy to tie the OUTPUTS of two different devices together. There is a chance they will short each other out. You need some type of isolation between them. The Balanced and Unbalanced Line Ins would likely provide the isolation you need.

If that is not an option, then it become complicated, and will likely require some type of Switch or more hardware of some type.

A simply RCA Line Switch would allow you to switch between the Pre-Amps. These are usually purely passive devices, so they are not directional. A simple 2-way switch can be 2 In/1 Out, or it can be 1 In/2 Out. These are also not very expensive.

https://www.amazon.co.uk/s/ref=nb_sb_noss_2?url=search-alias=aps&field-keywords=RCA+audio+Swtich&rh=i:aps,k:RCA+audio+Swtich

A simple rotary switch device assure that only one device can be on-line at a give time -

https://www.amazon.co.uk/HQ-3-Way-Stereo-Input-Control-black/dp/B000I8OOS8/

https://www.amazon.co.uk/s/ref=nb_sb_noss?url=search-alias=aps&field-keywords=RCA+audio+selector+Swtich&rh=i:aps,k:RCA+audio+selector+Swtich

That is probably the simplest solution to your problem.

Steve/bluewizard
I’m very much inclined to agree with you. A RCA switch of some kind definitely would appear to be the most obvious solution and the 3 way one you linked to on Amazon caught my eye but then when searching for reviews I became less keen on introducing something of that quality to the signal chain. Searches for something of more audiophile quality led me to the Schiit SYS which is ostensibly marketed as a passive pre amp for use with DACs and powered monitors but on the FAQ page it has this;

“Can I use it with a power amp?
Absolutely, you can use SYS to connect two sources to any power amp with RCA inputs, and control the volume.

Hey, I just want a switch, not volume control.
Turn the volume all the way up and use the switch.”

Then it also states;

“The downside to a passive preamp is exactly that—it's passive. That means there are no electronics in it. Which means it can't drive really long cable runs. If you're expecting to run 35' RCA cables to your power amp, Sys isn't going to be the best option. If you're running 6' cables to desktop speakers, that's not a problem. We'd be careful with anything longer than 15' on Sys, depending on the cable type.”

I reached out to Schiit to ask how they think I would fare with 1m long RCA inputs and a 50cm output on the SYS and the guy said;

“Signal degradation comes from the fact that sys is totally passive and has no gain devices. If your preamps have gainstages or at least buffered outputs that would be ideal. The main point is just to not expect sys to run super long cable runs by itself from weak outputs.”

I have no idea what gain stages or a buffered output is but I’m assuming that the cheap switch boxes on Amazon must function in the same way and there seems to be no complaints of signal strength degradation for these that I can see.

Does anyone have any insight on the gain stage functionality of pre amps? Do all hifi pre amps have one by default? I think that I will probably go down the SYS route even if my perceived view of its superior quality is down to its price and aesthetic.
 

BlueWizard

Distinguished Member
The Schiit SYS at US$49 should do a good job. I don't see a problem with that. But a switch is a switch is a switch. Still, the price is pretty reasonable, and the switch itself is closed, meaning it is sealed and not exposed to outside air and dust, and there for less susceptible to corrosion and picking up noise over time.

Looking at the circuit board, it has a large ground plane making it fairly resistant to random noise.

Technically the Schiit SYS is a passive pre-amp, but as you mentioned, you are not required to use the volume control. The Volume Control can ONLY turn down, without active circuits it can not turn UP.

On a quick search I found the Schiit SYS for £60 inc VAT.

Electromod - Schiit SYS

https://schiit.eu.com/preamps/sys

That is probably more in keeping with the quality of your other equipment, but relative to budget, it is up to you to determine if you are willing to pay £60.

Seems like a very good solution.

Steve/bluewizard
 

Mark.Yudkin

Distinguished Member
Here is a Photo of the back panel of the Rotel RB-991 -

https://img.usaudiomart.com/uploads/large/1064584-rotel-rb991-power-amplifier.jpg

Notice it has Balanced and Unbalanced inputs. If one of your Pre-Amps has Balanced out, you can likely feed one Pre-Amp to the the RCA and the other Pre-Amp to the XLR Balanced.
Steve: look at the switch in the middle of the photo. The OP would need access to the back panel of the power amp to be able to switch between his two sources, which is why it's likely not an option.
 

BlueWizard

Distinguished Member
Steve: look at the switch in the middle of the photo. The OP would need access to the back panel of the power amp to be able to switch between his two sources, which is why it's likely not an option.
We all have to make sacrifices for art. Though it seems as if he has found a solution, so all is good.

Steve/bluewizard
 

Kructuan

Novice Member
Steve: look at the switch in the middle of the photo. The OP would need access to the back panel of the power amp to be able to switch between his two sources, which is why it's likely not an option.
Reaching the back to switch from RCA to XLR is perfectly acceptable. Its struggling to swap out the RCA cables which is the problem because they do not come off easily.
 

RAM18

Novice Member
Hi

Am new to this forum.I am thinking of using this Schiit SYS as a switcher to separate my music for stereo and HT for movies. Need your advise on this.

So i have an onkyo RZ830 AVR which is connected to my XTZ A 2 300 stereo power amp. I have Klipsch 6000f RP front speakers currently connected to my power amp too for stereo music routed through the onkyo. I have a marantz cd ud 7007 player connected to onkyo. And jamo surround and front height speakers as well as my two klipsch subs connected to my onkyo

I am planning to get a Schiit Freya + preamp and node 2i. Now can i connect all my stereo sources to my Freya pre amp. This would mean my marantz and node 2i and are connected to the preamp and then connected to Schiit SYS. Also can i connect my Onkyo to Schiit SYS for HT.

And then I connect the Schiit SYS to my XTZ stereo power amp. So i can switch between the Onkyo for HT and node 2i and marantz for music routed through Freya + preamp

Does this also mean i cant use my subs for stereo as both subs are connected to my Onkyo for HT? Is there a way around this?

Sorry for the long note. Am just trying to see how i can make things work and if this Schiit SYS can be a solution. My aim is to use the Schiit SYS not as a pre amp but purely as a switcher so I dont need to plug and unplug cables from my power amp each time i listen to music or watch HT. I also hope this addition to the chain would not compromise sound quality.
 

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