More important than any one setting is how all of them come together. Depending on which version of LAME you're using, the settings you're using may be to blame, not just the lowpass value.
-ms is not recommended, because the Joint Stereo is better. Also, depending on what version you're using, -q0 may be a bad thing and -b320 may set quite different defaults.
Pick up the current recommended version of LAME (3.97 beta 2) and try the commandline -b320 without any extra settings.