So I've read a few things about the 400 and just wanna get my facts straight. 1) I've heard/read the 400 has a "crappy" DI. Can anyone elaborate on this. I'm not concerned about live playing, it's more about running from the DI to our Mackie mixing board for recording our jams. How "noisy" is it?? 2) The "best" re-tubing info I'm seeing is 6 x 6550 (?) and 3 x EH 12AX7s (low noise) and I shouldn't need any biasing adjustments. Correct? Which 6550s?? Svetlana??