I don't see the insides of amps as much as I used to-but here are my guesses
1st Crown Itech
2nd not sure-but I first thought Mackie but the front doesn't look right
3rd Crest Pro 200
4th QSC? not sure
I'll wait for a couple more replies before I post the answers but until then lets up the ante and include the specific model if your sure on your answer lol
The PLX2 (third picture) appears to be missing the big choke mounted on the sidewall (just to the right of the power tranny) though the mounting pillars are there for it. I wonder if that is only fitted in 230volt land ?. BTW It would be fairly difficult to differentiate an Xti2k from an Xti4k from this angle (all the others are quite unique).
M