Ok, let me preface this by saying I don't know what I'm doing, but I got DSP manager working brilliantly. Your mileage may vary and I'm not responsible if this messes up your device -
MAKE A BACKUP FIRST!
My current setup:
VZW SGS3 w/ the K1 base.
CM10 Official & CM10 Nightlies (I've also used this on ICS and JB based TouchWiz ROMs)
Stock SGS3 headphones (they sound fantastic w/ this DSP Manager)
V6 Supercharger with the new Maximum Overdrive Multitasking Mod (may actually hurt the DSP effects)
Imoeseyon's Lean Kernel (Experimental) 1.10
I've tried just about all the DSP Managers I could find, Beats Audio, AwesomeBeats, as well as the new AC!D add-on (v4 and v5). They either don't work at all or they severely distort the bass.
What Works:
Using CM10 at least, this will provide excellent audio control in most apps. I've confirmed it working in Google Play Music, Google Play Movies & TV, Plex, PowerAmp, Pandora and YouTube. You will know it will work b/c (using the stock headphones at least) it will literally hurt your ears with clean, powerful bass. I've noticed in TW-based ROMs the DSP Manager doesn't seem to work with Google Play Music or the stock music player, but does work with most everything else.
Issues:
The only issue I've noticed is the DSP Manager will randomly turn off after 15-20 minutes sometimes, but this is known CM10 issue, which is what this DSP Manager came from. Wiggling the headphone plug or actually unplugging and plugging back-in usually fixes it. Also, the Dynamic Range Compression only seems to work in CM10 (maybe other non-TW based ROMs), but it actually kills all the bass, so I don't even use it. I've also noticed that the DSP Manager only works on certain songs using Google Play Music, but I've only noticed this using CM10 and V6 Supercharger, so I suspect those may be the culprit; on CM10 stable with no V6 Supercharger, it worked great.
My settings:
DRC: Off
Bass Boost: Enabled, Moderate
Equalizer: Enabled, Rock
Loudness Compensation: Stronger (this made a big difference on the bass output)
Headset Virtual Room Effect: Disabled
Enjoy!
http://www.4shared.com/zip/68ZTKefC/DSPmanager-v3-SGS3.html