for me, i really like having power amp distortion. as long as the pre amp has a bit of gain. cranking the crap out of the power section of my jcm 800 really gives it a modded jcm 800 sound.
mp1 with el34 power amp is my fav. gives you that marshall bite
tried 6l6's kt66's. tons of low end and more hi fi, but no bite.