[MarkyMark]

I'm using these headphones with the Sony NWZ-S639F and NWZ-A865 DAP's. I'm wondering if anyone has found any improvement with using an aftermarket amp such as one of the Fiio models versus the onboard amps?
 
I've read that multi-armature earphones require the headphone output impedance to be close to 0, otherwise they aren't driven properly and the sound is coloured. I understand the NWZ-A840 series had a problem in this regard but can't find any specs for my own Sony players.
 
Any help appreciated. Cheers.

 

[some1]

Do they sound coloured to you?  Are you finding this setup too quiet for you?  If the answer is no then you probably don't need an amp.  One thing an amp should do is bypass the EU volume limit on the Sony players.
 
Nothing i have tried with my TF10's have left me thinking i need an amp to drive them, but as i say, the sonys have that stupid EU volume limitation.