Best company to mod your gear?

Try partsconnexion.com, they're still doing mods. I do lots of parts procurement with them.

Fine Tuned Audio / Video located in Winter Park Florida.....Kris Rhoades is the man. Visit his web site. 

I would proceed with caution regarding mods unless the modder has a track record with a particular piece of equipment. Like Modwright did for the Oppo DVD players. He’s perfected those mods and knows the end result.  Just replacing parts with more expensive ones may not result in what you’re after. Just my 2 cents based on past experience.  

Well, if I were to use external modifier, I'd have done my own research and suggest or insist on  my mods and/or particular parts. If you have unique unit wanting to upgrade, your suggestions could be better than leaving it to them.  I had forgotten about Modwright, I did use Dan for some dac mods many years ago, don't think they're doing mods anymore?

One advantage of using external vs diy mods is modifier should warranty his work, and more important service it down the road. Many techs won't touch modified equipment, I don't know what this insistence is based on, but there it is. If you could find local tech that's willing to mod according to your instructions that would be major plus!