volume level and xlr

I have a Simaudio I-7 integrated and a Supernova cd player. When I use xlr interconnects as opposed to rca's the sound level is lower for a given setting on the volume control. Before the Supernova I used an Audio Aero Prima cd player with xlr's and experienced the same condition. The xlr cable was the same in each set up. They were new Signal Cable Silver Resolution cables. I used them for at least 60 hours of listening before a final assessment of the situation. I have since gone to Signal Cable Silver Resolution rca interconnects. I like Signal cables. I use them for all my cabling; a good cable at a reasonable price, and Frank is great to deal with.
Two questions-
1. Is this a normal thing or might I have a problem somewhere?
2. Is there that much to gain from xlr's as opposed to rca's?
It is possible your amp is expecting pro audio levels on the XLr and therefore it is atenuated somewhat when you use XLR with a device that does not output pro audio (+4 dBU).

Roughly speaking, consumer uses cheaper components and runs at (10 dbV = 0.3 Volts) while pro uses stronger signals (+4dbU = 1.22 Volts). Pro gear can usually go up to about 12 to 15 volts while consumer gear runs no more than 2 volts.

Ii can't be sure - but this might be the reason and it therefore means there is nothing wrong with your gear.
Although I am not technically savvy enough to understand the specifics of your answer, I think I get it generally. However, I would think that Simaudio has their amps and sources matched.
According to the i-7 manual, each input has an independently configurable volume offset, programmable between +10db and -10db. Have you tried adjusting that, or checking to see what it is presently set at?

Re question 2, it depends on a lot of things (cable length, noise environment, whether or not there is a hum pickup problem, whether the components are fully balanced or just balanced at the interface, the quality of the differential driver and receiver stages, etc.). Those variables can result in the balanced (xlr) interface being either better or worse than the unbalanced (rca) interface. All I can suggest is to try it both ways and seeing which you prefer, if any differences are perceivable.

-- Al
The XLR standard output is 3 or 4 db higher vs RCA, so you must have a setting off somewhere as Almarg suggested. A true balanced cable in a balanced circuit has a lower noise floor and 3 seperate wires for +, - and ground.
Great question btw Valinar. My experience is very similar. I have an ASR Basis Exclusive phono pre that has both XLR and RCA outputs. When using the XLR outputs to my XLR inputs on my Denon CDR, the output is substantially less than when using the RCA outputs to the RCA inputs to my Denon. I prefer the XLR...overall much better sonic performance than the RCA. Though there are quite a few technical reasons that could easily explain why this is occurring, I would like to think that there is a mysterious force from planet audiophilicus preposteri causing this phenomenon. As silly as this may sound, having personally surpassed the highest level of subjectivity in our audiophile measuring capabilities...I have nothing more to base cause and effect speculation, other than just pure lunacy. Most of us have achieved this profound level...but are afraid to admit it. Cheers
You were right. I went into the software setup and reconfigured the volume offset setting. Thanks!
Aptquark, you know what happens to those that violate the prime directive by mentioning Planet 0. There should be a shuttle on its way now.

Me, I'll just mention that I am having a hard time distinguishing between the xlr and rca outputs of my dacmagic. There must be a difference, I'm sure, but I don't want to get teleported away like some people...

"The ballerina has no slippers" repeat..."The ballerina has no slippers"....... (The revolution has begun!)
From Supreme Commander of Planet O:

"The entire contents of the audio sphere known as high end audio will be removed from it's indigenous locality and transported to our home world, Planet 0, for extended examination and rectification."

"Copy the ballerina's soles are missing and will commence with the revolution at 33 1/3 speed."

Quantifiably Yours,
The All Knowing Supreme Determiner of Audio Malfeasance