I'm noticing that recordings I mix sound good (even instrument levels, nothing sticking out in a bad way, etc) on many different systems when the EQ is left flat, but as soon as I play with the EQ it creates massive changes to the sound, (ie. certain instruments go away or become overwhelming). EQ adjustments on commercial CD's don't seem to have this problem in general... Why does a home stereo EQ seem to affect my home produced recordings more than it affects commercially recorded material? And what can I do to fix it? Is this some fundamental principle of mixing/mastering that I'm missing? What types of tools should I be using to remedy this situation?