Tubes for Audio Research SP16L

Tubes age. The presentation softens some when they are 'old' and they can get noisy. The best thing you can do to avoid angst over slow degredation is to have a spare set on hand and, depending on amount of use, put the new set in every year or so and see if there is any meaningful difference. If not take them out and want another year or so.

You can get tubes identical (brand) to the ones you have, or if you want to change the tone you can consider other brands.

If you are asking these questions, best to go with Audio Research replacement tubes. I was trying to 'get into' tubes and bought an Audio Research SP-10. (15 tubes!) Then I realized that sort of tube-ness was over my head, and bought an Audio Research SP-15 (three tubes) (sold the SP-10) and will buy extra tubes to do just what "newbee" suggests.
The quandries of 'tube rolling' I want to leave to the adventurous.

Call Dave Gordon at AR, he's VERY knowledgeable and helpful--moreover a GREAT guy!