You asked about the VTL amps. Since they are almost 20 y/o, I decided to replace all the electrolytics before they failed. -Same value with a dynamicap bypass on each large power supply cap. The coupling caps were replaced with dynamicaps .47 mfd (8 in each amp). The input and driver coupling caps replaced with 1 mfd dynamicaps. If I had it to do over, I would use the Mundorf silver in oil, but 10 yrs ago, I didn't know about them. -Very expensive as well.
This mod was major work. Just getting to the underside of the circuit boards was a major task.
Have you done anything to your monoblocks?
-John