New Headphones or new DAC?

[TheDigitalRealm]

So, I've got a little extra money coming my way and want to upgrade my audio set up. Currently, I have a pair of Sennheiser HD 595's and a Xonar D2X. I listen to 192 KHz 24 bit files. I was wondering where I would hear the biggest improvement, in getting an external DAC+AMP such as a FiiO E17+E09K or getting a pair of Sennheiser HD 600's?

 

FiiO E17+E09K:

http://www.amazon.co.uk/FiiO-portable-amplifier-desktop-bundle/dp/B007X27WU4/ref=sr_1_1?ie=UTF8&qid=1392857300&sr=8-1&keywords=FiiO+E17+plus+e09k

 

HD 600's

http://www.amazon.co.uk/Sennheiser-HD-600-Monitoring-Headphones/dp/B00004SY4H/ref=cm_cr_pr_product_top

 

My budget is around £275.

[_ASSASSIN_]

your biggest improvment will be the HD 600, but you NEED a GOOD amp such as a o2 or just anything that is proper and can power 300 ohms.

[ShearMe]

your biggest improvment will be the HD 600, but you NEED a GOOD amp such as a o2 or just anything that is proper and can power 300 ohms.

 

Needs less amping than a 250ohm DT variant.

 

Headphones are always a bigger improvement than a different source.

[TheDigitalRealm]

your biggest improvment will be the HD 600, but you NEED a GOOD amp such as a o2 or just anything that is proper and can power 300 ohms.

My Xonar D2X (after a lot of software and driver work) finally delivers a, for the most part, uncolored sound. It will also drive 300 ohm impedance headphones, so I should be fine with it until I save up to get a decent USB DAC.