Now I finally know how to use it, I use it religiously.
I have noticed that even after fixing the wav pre master, after mastering it can again have peaks and dips in the spectrum.
Question to god....
Would it be recommended to use harbal again, post master to lose the peaks and dips created while mastering?
NOOOO!
HarBal is good for mastering GHETTO mixes that you need to listen to on the fly. What I mean is that if you're in the control room of a recording studio and can't get a good reference like you would in a professionally calibrated mastering studio, then it works. I draw a cutoff at 40 or higher and I'm good to go (remember that this will alter the overall effect of the mix, so spend some time to at least TRY to get a decent representation.)
For example, I can't get a good reference on anything below 40Hz if I'm standing in front of some Genelecs that are about two feet away from my face. I don't care how low you set the volume in the control room to effectively "master" the track, your ears won't hear a proper representational mix.
Remember, there's a reason you pay a guy at Sterling Sound a couple hundred dollars an hour. Because they do this shit properly.
The bass issue often happens when you burn the track to a .wav and play it on your car stereo. The muddiness evident with the subs tend to destroy the molecules of that jelly donut in your belly (you know, the one you just ate.)
HarBal allows me to make a ghetto-master so I won't get spontaneous combustion from the subs. I wouldn't base any life decisions on it unless you can't afford a mastering engineer. And from my experience, most purported low-budget mastering engineers don't have the right equipment or know what they're doing anyway. It really takes a trained ear to know what the fuck to do in a mastering session - something I would never try doing.