What's the output impedance of the headphones? I highly doubt an amp will boost the bass (the bass boost option in cheap FiiO amps completely destroy the sound).
Don't spend 5k to drive a 2k headphones!!
Give it a mid bass boost of 2dbB or less in EQ if you want more bass.
Don't mess up sub bass frequencies, the drivers possibly won't respond.
As Rezep already pointed out, these are already bass heavy, don't waste money on a desktop amp unless you plan on upgrading the headphones soon.
Use Foobar on Windows if possible, it has a good transparent EQ which doesn't apply any compression. Consider using ASIO4all as your default audio driver in Windows and configure it properly in Foobar.
C
How much are you ready to spend?
Come on buddy!! Don't guide him to the rabbit hole...@ OP, if you're enjoying music with your present headphones, use them till they break.
This is a very dangerous hobby!!