So would it be fair to say you feel the mod introduced no sibilance and kept the bass quantity(this is important because it seemed to me it would rob you of some low end.)
I have considered doing the mod several times to my 2k's and now thinking about ordering the kit for my 5k's. The last thing I would want to do is finish modding to realise it brought the low-end to "normal" headphone levels or rob it of impact which I didn't buy the Denon for. Thanks for the info!
I have been convinced for some time that the bass and midrange bloat isn't caused by resonance INSIDE the headphones, but the air cavity between the headphones and the ears. You can experiment by simply ever so slightly pulling the rear of the earpad away from your head while listening to music, thus breaking the seal. The more you lift, the thinner the bass gets. Ultimately, I did a simple mod to more permanently evaluate this sound. I'm not saying that the MarkL mods sound just like this, but this simple and temporary mod does reduce the bloat and clear the midrange, at the expense of adding a little sibilance. A description that's typical of MarkL modders here.