I would always buy a matched pair. Considering the future, most likely one going at a time, preferably a matched quad if money is easy (hah).. In either case, having your one good used one will give you the luxury of time in the future.
I assume you like the sound of your existing brand/version. Exact brand/version available so no surprises and spare is the same?
Want to try different brand/version? Buy from a source that will allow returns or exchanges. Different brands/versions do sound different. I am now exchanging some NOS Sylvania’s I bought and tried for some NOS GE’s I know I love the sound of. Brent Jesse lets you break them in, and exchange them if you want, others will also.
Break them in before you do critical listening. You can just turn/leave amp on, nothing playing. After 3 days, that is how they will sound.
Different brand? After breaking them in, as a test, I would put one new one in with your used good one. Balanced? Sound Great together? Have a method to listen to each side individually? Learning about the sound of each brand is good info.
I assume you like the sound of your existing brand/version. Exact brand/version available so no surprises and spare is the same?
Want to try different brand/version? Buy from a source that will allow returns or exchanges. Different brands/versions do sound different. I am now exchanging some NOS Sylvania’s I bought and tried for some NOS GE’s I know I love the sound of. Brent Jesse lets you break them in, and exchange them if you want, others will also.
Break them in before you do critical listening. You can just turn/leave amp on, nothing playing. After 3 days, that is how they will sound.
Different brand? After breaking them in, as a test, I would put one new one in with your used good one. Balanced? Sound Great together? Have a method to listen to each side individually? Learning about the sound of each brand is good info.