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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
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).

lanx0003
1,928 posts
 

Benchmark made xlr to rca cable with floating pin 3.

https://benchmarkmedia.com/products/benchmark-xlrfm-to-rca-adapter-cable-pin-3-floating?srsltid=AfmBOop5w8RyHbOW9YNHwBisaIDv2JQD9du5WloFp0u4g5U9T55SRauO

iseland's avatar
iseland
252 posts
 

Usually singel ended have half the voltage of balanced outputs. 

Amps have different gainfaktor, so there you have it 🙂

And no you don’t get higher gain by feeding single ended input with xlr output from pre.

mike4597's avatar
mike4597 OP
304 posts
 

Thank you all for your comments.  Clearly, no advantage to going with hybrid cables.  Once again demonstrating the value of the Audiogon forums.

rjinaz86323's avatar
rjinaz86323
48 posts
 

I am running a Linn ADMS/3 into a PS Audio S300 amp.  When I switched from RCA to XLR I picked up gain, as anticipated.  But it also seems that the quiet is quieter

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