I got my X1 back but I'd been spending a bit of time experimenting with it. Still need more time to burn it in.
My X1 actually had a bit more done to it than a simple checkup. The intelligence of Nelson's and Wayne's design became apparent when I asked if I could get a gain reduction in the low gain stage. Apparently the X1 is easily modfied to do this, so I had it done. I was getting too much total gain in my setup, so that I was maxing out my listening volume at very low control settings (this was with the 4dB gain setting). What makes the mods so sweet is that it can be configured afterward (by the owner) so that some of the gain reduction can be removed by a simple movement of mainboard jumpers. Not too shabby, although you'd do this at your own risk of course.
What I can say now that I got it back is that I can hear things more clearly at very low volume levels. Before, there was less of an ability to pick out small bits of detail. Now it seems I can hear things down there that I hadn't been able to before. At higher volumes the sense of clarity is also there. Additionally, of course, I now have a much more gain-friendly preamp for my setup and a much broader range of adjustment.
That and the usual praise for Pass customer support. They are one of the best companies I have ever dealt with as far as customer care is concerned. You can tell it's one of their basic tenents. If for that alone I would not think twice about considering another hunk of Pass gear.