I dusted off my HD650's that i bought for audio engineering projects, but wound up never using. i always found the bass to be tight and clear, but lacking in level - APO is helping with that!
here's what i'm finding to be a fun listen while still maintaining the spirit of the 650s. everybody's ears are different, especially in headphones, but here it is in case anyone would like to try:
Low shelf, 78 Hz, +8dB, .77 Q
Parametric, 80 Hz, -2.5dB, 2.5 Q
Parametric, 176 Hz, -1.5 dB, 1.1 Q
High Shelf, 9.9kHz, +0.9 dB, 1.2 Q
Parametric, 12k, -1.5 dB, 6 Q
edit after a lot of listening and bypassing the eq: i feel that this setting better serves the spirit of the headphone while giving me a bit more of what i'd expect to hear from my reference tracks. i've stopped thinking and am enjoying listening to the music now. what a musical, fun set of cans.
High-pass filter, 20 Hz, .71 Q
Low shelf, 78 Hz, +5.5dB, .77 Q
Parametric, 80 Hz, -2.0dB, 2.5 Q
Parametric, 176 Hz, -1.2 dB, 1.1 Q
High Shelf, 10.9kHz, +0.8 dB, 1.2 Q
Parametric, 12k, -1.5 dB, 6.7 Q