You need a VST host such as George Yohng's VST wrapper for foobar
Long time equalizer and supporter of this thread here. I've been in hardcore mode the last few days:
What you're looking at is part of my sound card's built in EQ settings. I have fb2k set up to route the L/R channels to their own ASIO channels. With this, I can set up EQ for each channel individually, and solve for problems that dual-channel EQ cannot. After I had the tone of the sound near perfect, I realized that my ears are both quite different (or the headphones themselves) and the soundstage was suffering. I've used a combination of pink noise and mono-mixdown music to help center specific frequencies that were off balanced. The result is pretty damn awesome.
^ xnor has also made quite a decent (and free) stereo EQ for foobar. Also, a non-manual (non-perception-based) alternative to stereo EQ to fix channel imbalances is the convolution method, outlined there: http://www.head-fi.org/t/566929/headphone-csd-waterfall-plots/855#post_8796228 (well, somewhere in that thread anyway), which I've not yet seen anybody else here attempt, but have had good success with myself.
My audio-technica ATH-M50 balanced EQ using SineGen and Equalizer for iOS:
375 Hz: +2, Q=2
3600 Hz: +3, Q=4.319
4500 Hz: -4, Q=4.319
5800 Hz: +2, Q=4.319
9100 Hz: -6, Q=4.319
The M50S Headroom graph for comparison (their regular M50 graph is the same)
Notice the dip between 300 and 400 Hz, the slight peak between 4 and 5 KHz, the dip between 5 and 6, and the peak around 9. I must have dummy head ears.
As for my 3600 Hz adjustment, the FR sounded like it dropped off a table after the natural peak near 3 kHz. I don't know if this is normal or not, but 3600 Hz sounded way quieter than any frequencies in its vicinity. Getting rid of that 9100 Hz spike really smoothed out the treble response. The other settings really don't make much of a difference.