Upgrade or Mod?

I'm currently using a Sony CE775 for SACD. Redbook CD's are being decoded using a Link DAC I w/ Audio Alchemy PS3 power supply.

The rest of the current system:
Stan Warren modified Adcom 5400 amp
Quicksilver tubed linestage
Magnepan MG12's
Kimber PBJ interconnects and 8tc speaker cables

While I like the detail/transparency, I sometimes wish I had a smoother, more laid-back sound (especially in the high frequency range).

Need comments/suggestions on whether I should modify the Link DAC or sell the entire set-up and buy a Rega Planet. The cost will be about the same either way.
This is not what you are expecting to hear:

While I have not heard any of your components, I have used both Kimbers and would suspect them as passing that type of sound. Depending on the equipment, they can be revealing/very clean or sort-of-"wiry" sounding. (Sorry for the pun, but they've been at my place for 10+ years and been used in many different spots.) YMMV.
you may buy Musical Fidelity X10 tube buffer $110+- on audiogon or ebay and use at the output of your SACD player for both SACDs and CDs. It will bring you the desired softness without extra spending and moreover will give you a possibility to bring back some bucks from Audio Alchemy components.
Stan Warren can also modify your Sony.
Not sure if and what mods are available for the particular unit you use, but have you considered modifying the Sony (Audiocom mods, Stan Warren, Dan Wright and others)? That way you could have your SACD improved as well.
Another method to get the sound you are looking for might be to try a REALLY good isolation platform like the Machina Dynamica Promethean. Machina Dynamica
I have heard the PBJ's and I think that if you upgraded to the Kimber Hero's or Van Den Hul for instance for interconnects, esp. cdp, you would smooth out your system quite a bit. Also try Van Den Hul speaker cable for a smoother sound. The PBJ stuff can tend to be a little bright and forward. It's also not shielded very well so it can catch interference easy.

Good luck.