FWIW - I recently bought a used Beresford TC-7510, which is the model that preceded the 7520. It has 2 RCA and 2 optical inputs, and no USB input. My Beresford had been highly modified by a local modder, K-Works. K-Works calls this the SuperBerry DAC. K-Works' Igor Kuznetzoff feels the Beresford is a wonderfull platform for mods. I think it sells for about $1K new. I have to say this is a marvelous DAC. It is detailed, smooth, quiet and musical. In my local audio club, this DAC was put head-to-head with a $10K DAC from MSB, and most of those present declared it a tie. Although I don't doubt better digital sound can be had, I think it will require a lot of money to get it. For now, I am off the upgrade-go-round, at least as far as my DAC is concerned. My transport is a modest, but quiet, Rotel RCD-02.