Two weeks ago my S2 ‘rebooted’ while in use. Upon coming back up I found that the USB icon stayed colored red, meaning that the computer was not communicating with the DAC - many computers later and many USB cables later I realized that I had a problem.
I worked with Sumiko for a few hours trying to get the DAC working with no success. When I told Sumiko that I purchased the DAC from Amazon through Audio Advisor I was told that they were great guys, easy to work with, etc, and that I should try to do an exchange through them instead of sending it in to Sumiko for warranty repair (I only had the DAC for +/- 40 days).
The guys at Audio Advisor were great - the S2 is currently out of stock but I shipped them my broken DAC and am waiting for the S2 to come back in stock for them to ship a replacement. I called on a weekday so I can’t speak for their weekend support.
I’m wondering if there isn’t a flaw in the USB design of the DAC? I was powered through the USB port of a MacBook Pro. I never had physical damage to any of the USB ports on the DAC and could always get it to power up through either of the USB ports. The DAC just never showed on a computer through device manager or lsusb after working fine for a month. Odd.