I just received my Orchard Audio Starkrimson amp today and this is what I purchased with it to convert the balanced to unbalanced and it also supplies an extra 8db of gain
Stereo RCA to XLR Converter (orchardaudio.com)
Okay to use RCA adapter on a fully balanced amp?
Not a XLR is better or RCA is better question BUT if I have an amp (Digital Amplifier Co) that is fully balanced and only has XLR inputs, if you use a converter and go RCA from a Preamp, are you losing out in quality?
Here is something from audioholics and their review of one of their amps -
"The MEGAschino is a true fully balanced differential amplifier from input to output. It is essentially two amps for each channel, and one amp per phase. This means it really should be used in a fully balanced system.The manufacturer supplies an XLR to RCA adapter, but these should not be used. If a balanced connection cannot be used, note that the amp cannot be driven to full power from a 2-volt single-ended output, the limit of most receivers."