There is a broad range of 12AU7s in terms of tone. It really depends on what you want to achieve. Then of course how much you want to risk. NOS and in reality many are lightly used tubes are a gamble, that virtually no seller will warranty, once you have put it in your equipment. Fortunately there is a current production tube that is supposed to be truly excellent. That tube is the Gold Lion reissue. A very good vendor is over on Audio Asylum named Jim McShane. (no financial intersest whatsoever)
If you want to get something really extraordinary chase down the Amperex 7613 from the early 60s and late 50s. They are a direct sub only from Heerlen, often made for computers etc so you will find Hewlett Packard etc. branding. Super clean detailed crystaline halographic extended really special. Of course IMO.
6922s are scarcer if you want really good older tubes anyway. The prices get insane fast. One great sub that I like which is more German Sounding Than British is the Mullard CV2943. Upscale Audio has them from time to time. That's a good place to look also at others. There may be more bang for your buck if you can use 6DJ8s.
Good luck, tube rolling can be a very slippery slope.
If you want to get something really extraordinary chase down the Amperex 7613 from the early 60s and late 50s. They are a direct sub only from Heerlen, often made for computers etc so you will find Hewlett Packard etc. branding. Super clean detailed crystaline halographic extended really special. Of course IMO.
6922s are scarcer if you want really good older tubes anyway. The prices get insane fast. One great sub that I like which is more German Sounding Than British is the Mullard CV2943. Upscale Audio has them from time to time. That's a good place to look also at others. There may be more bang for your buck if you can use 6DJ8s.
Good luck, tube rolling can be a very slippery slope.