Hi Dev,
The phono circuit in your preamp is the same as in the Phi Beta, which I'll receive on Friday. I, too, asked Brent about rolling the 12AX7s a few weeks ago and received similar info. One thing I'll add is that he said the back row, the inputs, play the greatest roll in sonics--back to front, in order of decreasing influence. The front pair, under the most stress, have the least influence on sonics and will have the shortest lifespan. He said to place the tubes you care about the least in that position. I'll probably start the rolling process by leaving the Chinese tubes there and placing my fav 1964 USA Amperex 7308 into the back because they have such great focus, resolution, and balance. Then I'll see what middle pair is best for tone. But, of course, I'll ultimately experiment with all positions
The phono circuit in your preamp is the same as in the Phi Beta, which I'll receive on Friday. I, too, asked Brent about rolling the 12AX7s a few weeks ago and received similar info. One thing I'll add is that he said the back row, the inputs, play the greatest roll in sonics--back to front, in order of decreasing influence. The front pair, under the most stress, have the least influence on sonics and will have the shortest lifespan. He said to place the tubes you care about the least in that position. I'll probably start the rolling process by leaving the Chinese tubes there and placing my fav 1964 USA Amperex 7308 into the back because they have such great focus, resolution, and balance. Then I'll see what middle pair is best for tone. But, of course, I'll ultimately experiment with all positions