HE-350's Help, My ears are bleeding

There’s a few mods that help this one.

If you want more bass, remove the sticker covering the hole on the center of the back of the driver. For me, it was too much.

If you want to improve the clarity, by a tiny amount, remove the fabric on the grills.

If it’s too bright, add layers of either toilet paper or paper towels between the pads and drivers. This one is the most obvious improvement.

Another mod, but it’s not free, is swapping the pads for brainwavs angled pleather. Little bit of bass boost, but giant improvement in comfort over those rock hard stock velours.