I've had the MS Pro for a little while now, and I think I'm finally going to sell my PS Audio DLIII, which has provided outstanding performance for me for a while now. I had the original Music Streamer+, and while it was pretty musical, I felt that it ultimately wasn't as transparent as the DLIII and lacked extension at both ends of the spectrum. This is not the case with the Streamer Pro. I feel that it is as clear a window into the music as the DLIII, while still being slightly more musical relative to the DLIII, which can at times sound slightly etched in comparison (although the differences are small - I really like the DLIII). The DLIII is slightly airier, in contrast to the slightly meatier, more mid-focused Streamer Pro sound.
I had some issues initially connecting the Streamer Pro to my computer - it would drop out when connected to my slightly older Lenovo T61, while performing just fine with my Thinkpad tablet from work. The issues with the older computer have largely gone away once I added a powered USB hub to the equation, but folks with older computers should probably be wary - these asynchronous DACs don't always play well with dated USB ports.
Another added bonus of the Streamer Pro is its relatively small form factor. I plan on combining the DAC with my TTVJ portable and (hypothetical) Livewire Trips to combine for a truly killer transportable / office rig.