If price is a criteria, then anything using vacuum tubes will be more expensive than the equivalent that doesn't use them.
If your goal right now is to reduce certain high frequencies, the best way would be with a tone control or equalizer. The cheapest way might be draping cloth over the tweeters. The most expensive and difficult way would be trying different amplifiers and boutique speaker cables. It's just a matter of time, budget, and what's fun for you.