Thanks for the link. Looks interesting

However, he'll only be able to test valves if he has a proper valve tester and knows how to use it. That may be the case, but it may not. If you're dealing with him again, I'd ask. Even if he has one and knows how to use it, however, he may be reluctant to go through all his stock, measure and find matched pairs.

Depends on both him and his business. However, I can say with some certainty that there's a BIG difference, in both sound and potentially good reliability, when comparing matched (balanced, which is a different thing again) valves with the opposite, especially in critical applications such as phono stages!

Marco.