HTC Audio Manager and replay gain

[Dojey]

So I've been using the HTC Audio Manager for a while now but always had issues with the volume being too loud. I finally got around to getting MediaMonkey and running the whole Level Track Volume business.
But when I listen to it, all the songs come at totally different volumes (leveled on "radio gain" or "track gain"). When I read up about it some more, it sounds like Replay Gain only works on players that support this feature. Is this true? And does anybody know if the HTC Audio Manager supports this?
Otherwise it sounds like I need to use something like MP3Gain to change the MP3 itself, not just the tags?
Thanks!