Just updated my Rust in Peace tone. Marshall Britsh 80 based. I have set on an allround tone, good for solos and riff also. Some of the solos may need some more boost on treble but here it is:
And also the other one:
witch is based on the Countdown to extintion tone.
I think that the must have tones of Megadeth are 3:
1) Rust in Peace "vintage" Megadeth tone
2) Countdown to extintion "modern" Megadeth tone
3) Youthanasia "crunch modern" tone
If you think i am missing the 3rd one, just roll back a bit the gain on the Megadeth TS v3 and you will get a version of it.
When i play a tout le monde at home i usually go for with a preset i call Twin X Metal (basically a 65 preset with gain at 4, delay and reverb) and a Metal Zone stomp (well, the zoom multi stomp model truly...) with less than half drive. It do a very good job and i can still use the amp eq to cut through the mix without really affecting the cruchy tone.
The Twin X Metal is no much difference with this: