Tubes for Audio Research SP16L

I have an Audio Research SP16L preamp I purchased new about a year ago. Since this is my first tube preamp, I am curious about tube replacement. Specifically, will the tubes degrade the audio quality prior to burning out? If so, is such degradation noticeable?

Thank you for your help.
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!

Your lucky with only 3 tubes.

I recently got the Sp 16, with 3 more for the phono stage (6 total).

Love the sound to death but I think I have reached my tolerance in regards of # of tubes I care to deal with in my system.

I'll be picking up a spare set at some point I imagine for comparison should I suspect a problem as Newbee suggests.

My tube DAC (1 tube) came with an extra alternate tube that greatly changed the sound in some positive ways, so tube rolling doesn't necessarily scare me, but at present I see no reason to change what came with the ARC.

Still, if anybody has some good info on alternate tubes for the ARC and how they sound different than the stock tubes, I'm all ears.
Thank you, all, for the good info.