How am I supposed to just replace one tube and throw out all that paid-for attention to detail? I guess maybe the answer is to pony up more money for ANOTHER matched quad. Feels like a very, very expensive endeavor that makes the tube game silly.
If the power tubes have a lot of hours on them and one tube fails, it's a good clue that the tubes may be near the end of their lifespan and it might be a good time to replace the set. If a single tube fails early on, a single replacement can be found that matches your existing set. Yes, tubes can be expensive. I don't want to replace my dozen six-pac tubes unless I have to. Even cheap tubes times 12 get very expensive. The cost of running tube gear may not be within your budget, perhaps you should think about going back to solid state. Tubes are not suitable for everybody.