Even if I did use tube amps, I wouldn't be boycotting Russian-made tubes. It's not some massive business. The people making them have jobs and need to make a living(...)
Any Russian product that is sold, domestically or in export, results in tax revenue which funds the military. Buying a Russian tube is functionally the same as buying ammunition to be used against civilians in their own homes in their own sovereign nation.
I don't necessarily blame caviar merchants for what a nation does, but on the other hand, taking a hit in sales is a lot better than being shot at.