Noise, Noise, NOISE!!!

[RJ Hanson]

This is my first experience with posting, so please be patient with me. I recently purchased an reconditioned NAD T752. It works fine for DVD movies, using a digital input. I'm having a problem playing music cd's. If I use the digital input, the first half second of a music track is muted while the unit analyses the source. Using an analogue input solves this problem. However, when listening to a cd in any of the Surround modes there is an audible buzz present at medium to high volumes, say above -15db. The store where I bought it was very understanding and replaced the unit at the first sign of trouble. Unfortunately, the replacement has the same problem. Furthermore, the store's demo apparently exhibits the same tendency.
I discussed this at a local high end audio shop and they opine that it may be a ground loop problem, but I'm stumped. Any thoughts?

[joel2762]

On my Sony system playing music using Coax I get the same problem cutting the first half second. Sa'll ya can do I guess! As for that buzzing I wouldn't know. There's gotta be something wrong. I'm not sure what it could be.