Thank you, it helps. My problem though is that I still don't know what kind of sound I prefer, because I only have the Beyerdynamic DT-770 Pro (which I like) and nothing else for comparison, and thus I have little experience with what "warm" and "analytical" means. But from what I've read, of the two, I think "warm" would be the safest choice for people not really knowing what they want, so perhaps I'll see if I can get my hands on a 5TX.
Personally I think you would be investing relatively much in your amp vs headphone, since the 5TX is twice as expensive as the Beyerdynamic.. IMO the headphones are always the most important link (and money should be spent accordingly).
Alternatively you could consider a cheaper Fiio model that would work fine in combination with the Beyerdynamic, and save the rest to invest in better headphones when you're ready for an upgrade. To me that would make more sense..