If you search, there are some good threads on modding a PL. I think they are pre-Evo but may still apply to Evo.
To continue to beat a dead horse though, I really don't think the supplied PL tubes are all that great - but ok.. I'm thinking that they expect most (?) will roll thier tubes anyway.
I did a lot of searches here and on google as well as the reviews on Upscale and also with Brent Jesse (and purchased from him also).
I'm still a bit of a newbie (but not new) and I would start with the music you like and what you prioritze in SQ and go from there.
I chose KT-150s for the extra low end but also to my ears sound good throughout the spectrum. However, (better quality) E34s are better in the midrange (sweet) and there are a bunch of others.
That said, I would start with the preamp tubes up front. I have Radiotechniques (sp) up in the two main slot and prefer them over NOS Mullards and Mazda Clittes. The Mullards were too bright in the upper mids and the Mazdas a bit too much treble IIRC. I have the Mazdas flanking the Radios on each side. Also, you have double the power tubes than I do ($).
My Evo 300 Int sounds a lot better to my ears than the stock tubes.
I heard my same speakers at a hifi show with a $20k tube amp. While the mids were slightly more clear, the highs and lows weren't any better and certainly not worth the $15k difference - again to my ears. My sound stage is better also but with all of this I'm trying to take into account that was a motel room with no treatment. It did sound fantastic, but not any better than mine (again, except more clear mids, but not $15k clear).
Anyway, I'd start reading some of the comments and threads and also call Upscale and email Brent Jesse.
