B&K amp differences

Has anyone compared the following B&K amps first hand?    I have EX 4420 and while great seems a little light in the bass.  Not a big deal but just wondering.

ST 140 the 105 w/ch w blue stripe
ST 202
ST 2140
EX 442  Had one of these  awhile ago but do not recall if it is much different then the 4420