nrenter---My thought was to do the comparison between the preamp outputs and the amplifiers in the system. Obviously it couldn't be done in a simple and direct way on the front end. As it happens atmasphere's preamp has only XLR outputs. I don't suppose using the RCA tape outputs would make for an appropriate comparison?
But let's suppose, as you suggest, that an appropriate comparison can't be done. Doesn't the position that balanced lines and XLRs are better just remain, as I suggest, an article of faith?
shadorne: There are all sorts of reasons to use balanced lines in a pro audio setting: Long cable distances, greater potential for signal pollution, etc. None of which exists in the typical home audio set-up. Which suggests that experimentation, rather than philosophy, could be a better way to answer the question.
From a rhetorical perspective, the dismissive attitude of so many of the posters here is remarkably similar to religious belief, or to beliefs about global climate change. It's an interesting question to try to figure out the psychological causes of such beliefs, but the beliefs themselves are merely that.