For what its worth, this information was volunteered to me via private email by an esteemed computeraudiophile member, that owns a very high end system himself ......
....... a friend of mine owns the full DCS Scarlatti 4 box digital stack. He had a chance to audition an MSB digital stack in his system. The MSB stack was as follows: MSB Diamond DAC IV with the optional FemtoSecond Galaxy clock upgrade (so the top line clock), the MSB Diamond Power Base and the MSB Platinum Data CD IV transport. The Diamond power base was used to power both the DAC IV and the Data CD IV transport. The Transport was connected to the DAC via a stock ethernet cable to the Pro I2s input on the DAC. My friend's system is very good - dedicated room, significant work done on the electrical power, Wilson Alexandria X-2 Series 2 speakers, Lamm amps and ARC preamp. We used redbook CD's to compare the 2 front ends. The net bottom line is that we both agreed that the MSB digital stack was a quite a bit better than the Scarlatti - from soundstage, bass, resolution, harmonic density of images, etc. And the improvement was very easy to hear. My friend was quite surprised by how much better the MSB was to his ears.
Now, what about the Vivaldi. I have another friend (but not local to me) who just traded in his Scarlatti front end for the 3 box Vivaldi front end. He told me that the Vivaldi is better than the Scarlatti - but not dramatically - but he can hear an improvement in its resolution. There is another post on the What's best Forum - same thing - someone upgraded from the Scarlatti to the Vivaldi and describes similiar improvements but not dramatic (both to soundstage and resolution). The MSB configuration that my friend auditioned, is not the top line setup from MSB. For that, you would want their Signature Data CD IV transport with its own separate Signature Transport Power base. (The Diamond power base that he used contains both a linear power supply for the DAC and a separate switching power supply for the transport. The Signature Transport Power base is a full linear power supply just for the transport.
Bottom line to me is that I would expect the full MSB digital front end to outperform the full DCS Vivaldi front end. I think I also read that on this thread that you have the EMM DAC2x. I myself did a comparison of the same MSB digital stack that my friend used to the EMM XDS1 CD/SACD player. I would guess that the sonics of the DAC2x with a good music server/streamer to be roughly the same as the XDS1 (perhaps the DAC2x is a little better). The MSB stack was, in my opinion, in my system, quite a bit superior to the EMM XDS1 (of course, it is more expensive as well). After I did that comparison, I actually purchased an MSB digital front end and I couldn't be happier with it.