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.
