I purchased them from Upscale Audio for $65.00 each. Initially the sound was comparable to the stock tubes but in another 2 hours the sound began to change especially in the mid-range. More detail so far.
I just installed NOS tubes?
I have just replaced my stock 6922's with some NOS Amperex 7308's green label in my BAT VK-30. How soon should it be before I hear changes in sound quality and what should those changes be if any?