I ended up trying Fidelia.
Improved audio quality, probably due to limiting and equalization. I did a very thorough test with one file comparing the recorded output from iTunes and Fidelia, and found greater perceived loudness along with some better response across the frequency spectrum. While listening I was also using different metering plugins to get a more accurate picture of what was going on in terms of volume and frequencies.
-Scanning my audio plugins took hours. In some cases it took over 10 seconds to validate a plugin, as was the case with many Waves plugins. I have around 40 of those, and they come in different formats like VST and AU, and different variations as well, such as Mono and Stereo.
-In some cases, audio was degraded and sounded terrible. Then the output would go silent. This was the case with a couple of high resolution WAV files. In order to get sound again I had to quit the application.
-I also had to Force Quit the application numerous times. With each restart a crash report was supposed to be sent to Audiofile Engineering, but I don't know if the multiple reports actually went out.
-There's no functionality to quickly rearrange plugins.
-Additional features cost more than the application itself.
I hate to give this a low rating, but this is terrible. Feels like a beta version. I prefer to use iTunes along with Digital Power Station, or with Jack OS X and DSP-Quattro and my plugins. This worked fine with MP3 files, but failed with high resolution WAV files.
YMMV. I'm uninstalling it. Maybe I'll try it again once it's 1.2 or 1.5.