Tube recommendation for Audio Research LS-2b?

Sovtek 6922 as the original tube in your LS-2 did not sound right to me, so I did a little research and as I suspected the original tube was a Chinese 6DJ8. As I recall it was actually a 6DJ8H. My favorite tube in the Audio Research hybrid preamps back then was a 6DJ8H from Penta Labs. I recall Audio Research explaining the preamp is biased for that specific tube and in order to properly use a different type of 6DJ8/6922 a bias adjustment is required. Without the correct tube or the proper bias adjustments the sound would become dull. Bias is adjusted by changing resistors to achieve the proper settings.

I have a ARC LS22 that I use sometime and use to use the LS2B. If you want a nice improvement and not spend big, try these. They work very nicely in the ARC gear.

http://www.tubemonger.com/Matsushita_Japan_6922_E88CC_Mullard_Tooling_NOS_p/591.htm

These are also very nice sounding in my ARC gear.
http://www.tubemonger.com/Tungsram_E88CC_6922_MINT_NOS_NOV_1973_HUNGARY_p/1108.htm

If you don't mind spending a little money.

http://www.tubemonger.com/Mullard_MPs_MINT_NOS_1967_MIL_7308_CV4109_E188CC_B_p/2000mb.htm

I also like the Amprex 7308's but they also are quite expensive now.

The Chinese 6DJ8 drew a bit more heater current then the standard Russian 6922 if my memory serves me. So a different value resistor was used for the Chinese tube. The Chinese tube was stock at the time that preamp was manufactured.

I switched my LS2B to a Mullard Gold Pin and it sounded great.

I had an LS 2b. Have a LS 5b as a backup pre

You really need warm tubes for the LS2

nos telefunkens,mullards and amperex from the sixties worked like a charm for me