DAC1 or DAC1 USB?

I have decided to try out the DAC1 in my system. Does anyone have any experience with both versions of the DAC1? I have been told by Benchmark that a few things were changed from DAC1 to DAC1 USB but I find it hard to justify a 30% increase in price especially when I do not plan on actully using the USB option at least for now. Any thoughts? Thanks in advance.

My very modest setup:

NAD (5 disc changer)
Stratos Amp
Harbeth 7ES II Speakers
Rotel 1055 (used as peamp, looking to use the DAC1 as a pre and dac)