I own VTL 450MKII and before that VTL 300. Both products were purchased used, When I had a problem with the 300's I called them. VTL was reluctant to help me because I did not buy it from them. I took the amps to them and they verified no one had altered them and agreed to repaired. Over the years of upgrades and minor repairs I became a valued customer. On one of my early visits I was given a tour of the facility. VTL is a small company and they are in the business of making money. If you buy new from an authorized dealer you will be a customer and treated as such.
Funny, If I have an issue and call, one of the first questions is "Where did you get the tubes?" What a wonderful way to disarm someone. LOL