I'll say this, just got in a used Gustard X20U DAC, and the stock X20U DAC -> modded Gustard H10 amp -> modded TH-X00PH combo is absolutely SPECTACULAR! SO much detail and precision with a much smoother sound and the BASSSS - high precision IMPACT better than I've ever heard out of the TH-X00PH with new level of low end extension. If you ever have a chance I would highly recommend trying out the X20U DAC with H10 amp (preferably with different opamps than stock being used - using Burson V6 Classics in mine).
CamperIVMy TH-X00PH has Lawton dampening applied (driver housing pieces only), Jmoney V3 sheepskin pads, and custom in-pad attenuators that are crescent moon shaped which slip inside the ear hole. The Version 3 Jmoney pads I value more than the headphones. Here's a response graph of the configuration: