I mean it's obvious that digital out is far superior to anologue, as long as the AMPS DAC is good.

Not that obvious. I mean, plasma torch is superior cutting tool to an ax, which in turn is superior to kitchen knife, but if we just have to open a letter, all three are overkill and the first two actually won't do the job.

Over the typical distance, in relatively noise-free environment and with firm relatively oxide-free cable contacts digital vs. RCA will only show difference in DACs. (Which, of course, means that you are right and we should test both over RCAs unless we *want* to compare amp DAC to the one in empeg,)