There are certainly some gains to be made on the supply side of the SMPS... however, are you using any analogue features of the unit? If it's digital running only then I'd refrain as the most significant gains are to be made in the analogue domain.

You may actually lose overall as one downside would be mains supply voltage variations which would now affect the unit in the absence of a mains regenerator like my PPP.

I'd consider how to get very clean power to the SMPS, also EMI/RFI shielding inside the unit. My Weiss Medea DAC had a box within a box to minimise this. I've heard some use of a special paper but can't remember enough to comment and haven't used it myself yet...

This is one area where (IMHO) the Soolool Control 15 unit could be vastly improved - the audio board with its clocks etc sits directly above a CD ROM drive and adjacent to a spinning hard drive.... no shielding present at all...