I have had a pair of VPA's for about 3 years and a year ago 1 tube went bad and I replaced with tubes from Sophia Electric. They have tubes from Shuguang in China and a matched pair for $210 is great. I installed the tubes and had to adjust the bias somewhat and realized then that they were better and run cooler than the orginals. I would do it again. My VPA's were made before the KR tube came out.
Reliability issue - Nagra VPA power not KR tube
I have a pair of Nagra VPA Type I on evaluation. I ran over the weekend. The chassis heated up to well over finger warm. Tubes are obviously very hot - 535 F. My friend that has had a pair for 4 years recently had a major issuethat costed him $ 2,000 to repair. As part of my evalution, I am curios to hear from other VPA owners, what reliability issues they have had and the costs to repair them. Are these amps one should avoid from a reliability point of view. Thanks