I run XLR between preamp and monoblocks. After using for some time only RCA between DAC and Preamp I decided to check XLRs. With equally expensive RCA and XLRs the difference was subtsantial. Initially it was hard for me to say which one I like more as they offered tottally different musicality. And on top the aforementioned gain with the XLR further blurred the picture. I do not understand a lot about harmonics, but noticed that although the treble was somehow more fluid with the RCA it was also more fatiguing at higher levels. Probably due to different harmonics. XLR delivered more focused sound and definetly was more quiet. I lived for some time with both switching back and forth, but a bit surprisingly for me I left with no regret the XLRs in my system.
