The whole point of getting a DX100 is that it's an all-in-one solution, hence it being the size of a brick. Why would you get an additional amp? The external one suffices. However even if you wanted an external amp, $800 for a portable amp is ridiculous. The Leckerton UHA-6S is $350 and you'd be hard pressed to see huge gains over its performance without sacrificing portability. You've also listed the most expensive CIEMs around. The UERM is still summit-fi grade and costs under a grand. The JH16 Pro Freq-Phase is around $1300. The FitEar TO GO! 334, one of the best universals ever made, is $1300. A reference 8 cable? Unnecessary. Stuff from BTG is much less and just as good I bet.
So here's my more reasonable take:
Sony F806 Player: $300
Leckerton UHA-6S: $350
FitEar TO GO! 334 or JH16Pro Freq-Phase + shipping and audiologist costs: $1300
Which comes out to under $2000 and is most definitely summit-fi.
I was just making what could be the most expensive rig, not really logical. I would be pretty happy using the PP6 out of my phone or the PRM or the 335DW (which my only gripe against it is being sold only on Japan). In fact I decided to jump the around 1k step and go for the best cIEM available, but they make my wallet cry, lol.