Bit Disappointed in NAD

I have a C375BEE integrated that I bought awhile back that I like quite a bit. Built a new house, so my system was in boxes for awhile. Finally finished the house, so I unpacked my system and bought the MDC DAC 2.0 card from Crutchfield to add to my amp. I specifically bought this DAC so I could stream from iTunes via the USB input on the DAC. Installed the DAC, and right away noticed a significant buzz ONLY on the USB input (buzz rises/falls in step w/ volume). Tried the phono and optical inputs on the DAC, and they are fine, no buzz.

Contacted NAD, and was told to bring the amp and DAC to one of their authorized repair centers. Did so, and was charged $65 for a diagnostic fee so they could tell me:

• 1) Yes, the USB input buzzes
• 2) No, the unit is not repairable
• 3) No, there are no more, since the DAC has now been discontinued
• 4) The best they could do is send me a used DAC 1.0, which only supports 96kHz sampling instead of 192kHz on the 2.0

Now realistically, I doubt I'll be able to hear the difference between 96 and 192kHz. But I'm disappointed that I bought a product from what I thought was a reputable company, and even though they agree it's defective and is still under warranty, the best they can do is substitute an older, inferior product. I'm also really surprised that they don't even attempt to repair these. Personally, I find that these days we live in a bit of a "throw-away" society, and would have thought an electronics company with a reputation like NAD's would have been the exception to that.

It's only a $250 part, and maybe I'm just frustrated because I haven't had any music in over a month now, but I felt like venting a bit.