Simaudio 300D and 300D v2

Is there a difference between the two versions other than the improved USB interface in the v2? I will call Simaudio tomorrow, just curious if someone knows. Thanks.
Simaudio told me that while the USB interface is the most significant upgrade, that there are many across the board improvements also...
I have heard both and I thought it was a considerable upgrade to the 300Dv2. That is the one I own, the 300Dv2. I thought the first version was an excellent dac and feeling no need for any better, but you know. I feel the 300Dv2 is noticeably better.