Well normalize is actually made to make quiet songs loud, so making all songs quiet is bound to fail.Also it only works with MA 3.00 or later, but still, like I said above.
Anyway I read on the monkeys audio forum that some kind of replay gain embedded in the tag is planned for the next release(along with a higher compression option), all we can do is wait.
Personally though my APE files play a teeeeeeeny bit softer then mp3's.(don't have any mpc's)
(All my APE files and mp3's that I have on this current computer are freshly ripped(new pc, others are on CD's)
I rip to APE, my dad to mp3(he wants a lot on one burnt CD, I want hq)
It just so happens that me and my dad both independently ripped two same albums.So I compared songs of the two.
My configs:
All ripped with EACsecure(latest version, freshly downloaded last week), no normalizing.
APE encoded with latest MAC(downloaded three days ago), high setting.Playback thru winamp plug-in: normalizing disabeld.
MP3's encoded with LAME 3.92 setting: --alt-preset 160.Playback thru winamp, default settings.
I have winamp 2.81, I use all the default settings.(haven't tweaked it yet

need to install my plug-ins.
If you have replay gain on vorbis and mpc, maybe you should set it to a higher level to accomodate your MA files.