TRL or VSEI Level 4 for Sony S9000ES

For what seems to be called redbook CD, I take the digital out from the Sony through the DACs in the Proceed PDSD, becuase this gives a more open and transparent sound and better sountstage than using the Sony DACs. For SACD, of course, the output from the Sony is analog, and uses Sony's internal pulse-width DACs. The redbook CD and SACD sounds are a bit different, perhaps the SACD might be warmer, the redbook CD more detailed.

I really like the Sony S9000ES , and am wondering about having it modified by TRL or VSEI. There seems to be a substantial difference in cost. Your thoughts, preferences, or recommendations would be appreciated.