Audio Research LS-22: Best Tubes for this preamp?

Have you read this in-depth review of 6DJ8/6922/7308 tubes in Audio Asylum's FAQ section:
http://www.audioasylum.com/scripts/d.pl?audio/faq/joes-tubes.html

Well it doesn't answer your question directly, but will give you a broad overview of each tube's strength and weakness. I've tried most of them on my ARC LS-2B mk II, and I agree with most of Joe's assessments. My favorite is the Mullard Master Series 10M 6DJ8 which is not reviewed by Joe. This tube is very rare. I was just lucky to find one at a local electronic store. When it dies, I will be replacing it with my second and third favorites: Amperex 7308 whitle labels, and Amperex 6DJ8 orange globe lable.

FrankC

I collected all the tubes I'll ever need two/three years ago on eBay, online dealers, local electronic surplus stores, etc. I even bought an used military TV-7DU tube tester and had it recalibrated.

As the supply is depleting, you will have to pay a lot of money for good NOS tubes. Kevin Deal's a good source, but I'm not sure if he's got that much in stock. Check out www.audioasylum.com's homepage and the FAQ section. There are some reputable dealers there. If you are currently using Sovtek, you will hear the difference even when you just get the Sylvania JAN tubes, or the Russian NOS tubes (I think it has the designation of 6h-23N). These are much cheaper than Amperex/Siemens/Mullards, and much more readily available.

FrankC