For Gizmo (or any remote MC feed) to be useful to me, it must use the entire DSP output chain, so the remote audio is identical to what I'd hear locally from MC.
My DSP chain uses format conversion, ReplayGain, a compressor plug-in, and sometimes an EQ plug-in (or a combo dynamic EQ+compressor). The output of this is "MY MC" sound -- what I want to hear no matter how I'm accessing MC's output.
sometimes there's not quite enough volume on a phone, so anything that might turn lots of songs down could be objectionable.
In my early days with ReplayGain (years ago) I was having this problem, traced it to a few "bad" tracks that were way too loud. I edited the tracks (used an audio editor to "normalize", which seemed to work without detriment). It was definitely better to fix the too-loud tracks rather than have the entire library's average volume dragged down. I found the oddball tracks via a view sorted by ReplayGain.