boosting amps. always necessary?

really depends on the player and especially the music.
I used different things for the same project (everything distorted, with only "one" sound).
So one song had a TS in front, the next song didn't the third song had 2 tracks with and two tracks without TS.
All in all they sound very similar but the first song had more fast single note stuff, the second more open chords and the last one-yeah, a mix :D
I never liked the sound of a boosted Engl, but I almost never heard a Rectosound without a boost in front that I liked.
Loved the old JCM800 in our old rehearsal room without a boost but with EMGs for Slayer kind of stuff, but hated it for my own stuff.