In case that you have not read this classic thread on DAC1, here it is: http://www4.head-fi.org/forums/showthread.php?t=78848&page=7&pp=20
Note that Benchmark's Director of Engineer explained, "... This is also why the DAC1 will not benifit from high tech AC line cords and/or AC line filters." This is from Message #137. Read the whole thing, it's fun. The XLR to RCA trick is no longer required for new DAC1 which has low impedance RCA output.