How to improve the sound of VTL2.5?


Any suggestion on how to improve the sound of VTL2.5? Especially on the high?
mark
I just finished talking to VTL about possible improvements for my Vtl 2.5 and they (actually she) had a couple of ideas.

Since one of my tubes are really noisy, it was suggested to replace all 4 tubes ( 2 12au7s, and 2 6350s). Is it smart to change both sets of tubes at the same time? I don't know if the 12au7 and the 6350 have the same life span or not. They are about the same size, but obviously do different things. They also cost $15 each, which for currently manufactured tubes, seems to be a bit high.

The other option is to upgrade the caps on the preamp with, I believe, ?MIR? caps. This costs $200 and is suppose to really improve the overall sound. Does anyone have any experience with this type of upgrade? Does $200, parts and labor sound reasonable?
In addition to the usual suspects (see the two responses above), it may be something else, like your source. I recently purchased the GamuT CD-1 and was floored at all the new found music!
Sounds like a change of tubes, cables, powercords, or isolation support is the routes you have. What speciffically is bugging you and whats the rest of your system?