Upgrade recommendation. Richard Gray or Mcintosh.

Hi.. What should I upgrade first to get the biggest sonic improvement. I am considering upgrading my power conditioner from monster hts2000 to Richard Gray 1200 OR upgrade my Onkyo 919 (pre-amp)to the Mcintosh C42 pre-amp. your advice are greatly appreciated!

My current set up are:

B&W Nautilus 803
Mcintosh MC 352 - GREAT AMP
Rega planet 2000
MIT cables (shortgun through out)