The SCD-1 is a superb transport, better than many pricey separate transports--it certainly beat my previous transport, a Levinson 37, by a mile. Playing CDs from its digital out to a dCS Purcell-Elgar combo, which I had prior to getting the Sony, easily beats the Sony's own CD playback (it better at those prices!). But you're missing a key point when asking if people are using it with a separate DAC simply because the SCD-1 is a great transport--it's also a fine SACD player, and you practically get that for nothing. Can't answer your questions as to mods, but I'm presently auditioning a used Classe Omega SACD player, built on the same Sony transport as the SCD-1, and it is a noticeable improvement in most key respects over the SCD-1. Even though Classe is a major manufacturer, and obviously redesigned the hell out of the entire unit, it does prove that you can take the SCD-1 and get a lot more out of it. As to what, and how much, and from which modifier, I can't help you, but good luck. The SCD-1's out there are great acquisitions.
