you could hook up a hifi system / shitbox / or alternative speakers next to your main monitors and switch to it ocasionaly.
this way you'll have some other point of reference.
you'll still have to go out and listen to your mix on as many systems in as many spaces and levels as you can find
untill you know how your decisions in your room/speakers translate elsewhere.

I would recomend that you focus on creating a mix that rings nicely even before you start mastering (and recording well before you mix).
it's pretty good for practice not to master while you mix because a master compressor can seem to "cover up" mixing mistakes,
but actually it doesn't.
good luck.

by the way, the comment about waves is uncalled for..