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.
Regards,
-- Al
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.
Regards,
-- Al