I've been meaning to do this for a long time. Managed to do it now. Anyhow. I decided to equalize my HD600s to performing a simple LMS algorithm. The size of the FIR selected was 2000 taps and decided to roll off above 20 kHz to avoid corrections at frequencies the driver cannot handle well anyway. The steps I took are as follows: 1) Measure the HD600 cans both left and right channels and export the impulse response in .WAV format. 2) Load the impulse response in Octave (Maltab is better but I don't have it a home). 3) Perform LMS algorithm (2000 taps) on each of the channels. Target white (flat) response. 4) Make sure things converge and look awesome. 5) Save filter coefficients in .WAV format. 6) Install and configure "Convolver" in foobar2k using the .WAV format filter coefficients. To measure I played white noise and measured using another computer with REW's RTA. Here are the results (ignore dB scaling): Unequalized Equalized Right channel: Left channel: If I move the mic/cup coupling a bit I do get a bit of degradation. But not horrible and still better than unequalized. Here are three equalized measurements at slightly different positions vs non-eq HD600: How it sounds with equalization? Much less boomy, more brutally revealing, more presence. I don't feel things went down south. It's a different signature for sure. And again, a brutally revealing signature. Good recordings sound awesome. But most of what I have is not well recorded to start with. IMO the HD600 is already a very good neutral sounding headphone relative to other pieces of shit. But it is not perfect, and it does have a little of a warm signature. Equalizing to flat takes care of this. I may target less flat, more tilted response next. But IMO this shows what equalization can do.