Hello, I just purchased a Rotel 1520 integrated amp, I am setting it up to my iMac and have ALAC and FLAC files for music. My system is in the living room of an apartment (about 12x13). I have B&W CM5 speakers. I purchased a new Peachtree DAC IT for $450 but I cannot hear any sound difference using it connected via USB to iMac and RCA cables to Rotel amp, I switch between the internal iMac sound card and DAC IT and hear no difference at all, I have tried regular mp3s, FLAC and ALAC files, I changed the MIDI settings to 24/96 and 24/48, still sounds the same with or without DAC, I even installed Amarra 2.2, no difference in sound. I have used two sets of USB cables and two sets of RCA cables. Any suggestions? I am willing to buy another DAC. Thanks