What headphones did you mod?
I'm a big proponent of modding, but the more in depth you get with it, the more you're likely to ruin the sound. If a headphone needs that much modding, you're generally better off with a different headphone. Most of the mods I've seen, you can accomplish the same thing with tak and possibly some cotton balls while being fully reversible (plus you can fairly easily adjust it in either direction) and costing much less money. It might not be perfect, but if nothing else you can see if you like it, and if you don't can either adjust it or remove it entirely.
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I will admit that some popular mods have never sounded very good on any headphone I've tried them on, namely stuffing the earpads. It causes things to get really echto-ey and distant and kills the bass (the only ones that it was listenable were on headphones where I had upped the bass or had too much bass stock, but it makes it so much more fatiguing to listen to and often gives me a headache).