Echo/Static on Analog Line

I have a new V3000 installation using 5.0 code. 4 phones, two analog lines, 8-Port OfficeConnect switch with 802.1p capability, and inline power injectors. We started out from the git-go with echo problems on the analog lines which were quickly isolated to high loop current (44 ma) on the CO lines. Phone company was dragging thier feet eliminating the high current, so we put attenuators inside the demarc to bring the loop current down to 24 ma and cured the echo. There is one guy there that has a booming low-pitched voice, and he's a little hard of hearing so he always turns his volume all the way up and talks loud. As a result, he hears "static" in his sidetone when he's on a CO call. Conversations between extensions are fine. He is adamant that it's "got to be fixed", and to be fair, other systems that I've tested handle this type of overdriving volume on the CO lines very well. I've tried attenuating the line further, experimented with the audio controls to put some pad in the input gain, and nothing seems to effect the problem one bit. Anybody else seen this? Anybody got any ideas?