After giving it some thought, I switched to the DAC1 HDR. I chose the USB initially because I wanted the balanced digital input, but then decided the muting functions and the better potentiometer were more important.
Speaking of important, Guitar Center is running a coupon special for $150 off purchases of $799 or more until 12/24, and remarkably this coupon is good on Benchmark products. I've been thinking of getting a DAC1 for a few years now, and I've never seen a discount anywhere. Period. Full MSRP is it, and the best you can do is free shipping. So if you are thinking about a Benchmark DAC my advice is to buy now.