I had the modified DI/O, the first mod was done by the same gent that mod'ed Alberts. In all fairness, those mods really didn't make much of a difference. Mark's mods were elementary, like most of the mods that you read about on the various audiowebs. I'd sent my unit off to Kevin Morris (515) 288-8464, who redesigned the some of the circuits altogether. It has been too long since I'd had this done and can't elaborate on the entire series of mods done, (which is the only reason I included Kevin's phone number), but remember that one included adding a jack for an external clock. The sonic difference before and after Kevin's mods were dramatic, and sonically far superior to the unit you'd had, Albert. Syncing the external clock to both the transport and the DAC was a large sonic benefit, as you can imagine. The Kevin Morris modified unit is what Don had bought, so no clear comparison between yours and his could be determined. I know first hand, as I'd owned them both, (actually the same unit, but you understand).
I'm no longer using the DI/O, having moved onto another format. I'm one of the guys waiting for Ed Meitners DAC6, which should be delivered around 5 or 6 weeks from now. My brother Paul uses the eight channel Meitner DAC8 MK4, the latest pro version.
Kind regards,
Brian