You set the Bar so high at Home. Have you tried the PSB's with your home rig? WIth Tubes in the Mix I would be curious if the PSB's sounded close to the th900's on your home rig. Getting a tube sound on the go may be hard I have not seen many mods outside of the cabling. And I am not that adventurous to tear mine apart. A pad swap may be interesting. Since your current pads are worn maybe removing some of cloth in front of the drivers would change things a Bit. I saw some people do things like that in the Grado threads. I have not seen any aftermarket direct replacements maybe some people know of others that may be subbed ??