No, that's not mastering -- it's still a mix issue. Mixing allows you to produce a recording that should pretty much sound the same everywhere. Like most of us (or at least me), you probably have not taken the time to acoustically measure your room to see if bass builds up and/or there are peaks and nulls. The way to overcome that is to acoustically treat your room, get a monitoring system you can trust and to find the best place in your room to record/mix.

I have not treated my room yet, so I am also stuck trying to play things in many different environments to get the best trade-offs in mix decisions. I have been reading about acoustic treatment for about a year now and I think I know what I have to do -- but I just haven't spent the money/time yet to get it done.

Now at bandcamp: Crows Say Vee-Eh @ bandcamp or soundcloud: Kevin @ soundcloud