Hi Knghifi,
did you get your other tubes that you were waiting for.
What have you settled for in your pre.
Thanks for sharing.
I have found in the past when changing tubes in other gear the outcome has allot to do with the rest of my set-up, every set-up being different in one way or another so the out come not always being the same.
Personally when I heard the Sig. MK2a paired up with the Statement 450 mono blocks there was nothing at that point that I wanted to change, I liked how Kevin voiced them.
That being said I'm open minded so down the road tube rolling is most defiantly an option, fairly in expensive way to change the flavour specially when we are talking in relation to the pre-amp, time will tell.