Your best bet is XLR. I have two Aurender streamers and really good DACs. The difference is likely to be subtle but the cost substantial. On my Aurender W20SE I use the AES… it sounds a bit better than the Sp/DIF and USB. I think you have to look at your budget. If going RCA allows you to upgrade a component more quickly, than do that. If you are looking to the future of a much better system go XLR. Balanced is getting much more pervasive as time goes on.
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