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Would switching from RCA-RCA to XLR-RCA from Preamp to Amp result in higher gain

Need some advice and knowledge here.  My preamplifier (Rogue RP-7) has both XLR and RCA out--two pairs each.  My mono bloc amplifiers (Odyssey Kismets in Stratos cases) have only RCA inputs.  When I switched from a power amp with XLR inputs to my current amplifiers, I noticed that I have to turn the volume up higher to achieve the same sound levels, about 20-25 points higher per the preamplifier screen indicator level.  My cable runs to my mono bloc amplifiers are about six feet and 15 feet.

 My first reaction was to sell the Odyssey amps and go with either Van Alstine M225s or Schiit Tyrs, but the Odyssey Kismet's sound so wonderful I don't want to let them go.  I suppose another alternative would be to have Klaus build another set of these amps with XLR outputs, although  the amps are not balanced internally and there would some loss involved.  The other option is to buy XLR to RCA interconnects, which is what I am asking about.

My questions are:

1) Would switching to a pair of decent quality XLR to RCA cables take advantage of the (usually) higher voltage of the preamplifier's XLR outputs vs the RCA outputs and let me reduce the volume level on my preamp?    

2) Are there any downsides to having to turn the preamp level up so high with the RCA interconnects?  I don't really hear any increased background noise at the higher preamp level.

3) Should I expect any other downsides by using hybrid XLR/RCA cables?  

Manyi thanks for your responses.                                                                                                                                                                        

mike4597
cleeds
6,548 posts
 

There would be no advantage to using XLR>RCA, and no disadvantage to your present setup given that it sounds good to you. There's no downside to having to turn your preamp up louder provided it can maintain good s/n, which apparently it does.

erik_squires
17,543 posts
 

The biggest issue with too much gain is usually noise.  This is particularly bad with preamps, that force you to keep the volume knob down to 9 o’clock or less, and make it hard to make subtle volume adjustments.  

Turning the volume up, higher, means you have less gain in the pre and hopefully less noise than you would with a higher gain pre. 

It may help you to understand that internally most preamps have fixed amounts of gain, and the volume control only attenuates it.  This fixed gain = fixed noise. 

soix
11,233 posts
 

As long as you like what you’re hearing you’re fine. 

lanx0003
1,928 posts
 

Like most responses, there’s no real advantage. The RP-7 is indeed the first balanced preamp made by Rogue. However, if you use an XLR-to-RCA cable, only one leg of the balanced signal is connected to the single-ended RCA input. You’ll end up with essentially the same output level as the RCA connection.

What’s not mentioned above is the potential downside or risk of using a hybrid XLR-to-RCA connection. Since “the sophisticated electrical design is based on pure class-A tube amplification with MOSFET output buffering to provide huge drive along with a super-low output impedance,” (as said in their website) both legs of the XLR output may be actively driven (confirm with Rogue to be sure). If that’s the case, and you use a standard XLR-to-RCA cable,which shorts (ties) the cold leg, pin 3, to ground (pin 1), it could place undue load on the output stage and stress the active output stage over time.

The safe bet will be to use RCA to RCA cable.  If you must use XLR to RCA, make sure the pin 3 of XLR to RCA cable is floating (not tied to pin 1).

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