Quote:
I already have an Audio 2, it's great for performing but the headphone amp is decent at best
and I've tried a Focusrite Saffire PRO 24 before which is around $300 for 4x6, wasn't impressed and the bundled software was messy
If you are certain you do not want any inputs at this point in time then you might want to look at the Native Instruments Audio 2.
http://www.native-instruments.com/en/products/traktor/dj-audio-interfaces/traktor-audio-2/
I have for use on the road with an ultrabook running Ableton and Traktor. Clean and powerful sound. It has two separate stereo outputs which can be similar or different depending on what you want at the time. Pretty good value @ ~$100 plus a 'free' copy of Traktor.
If you do need ins just in case probably the most cost effective solution atm is the Focusrite Scarlett 2i4.
http://us.focusrite.com/usb-audio-interfaces/scarlett-2i4
Considerably more expensive @ ~$200+ but you do still get 2 stereo outs and a lot extra including a great suite of plug ins.
ed: correction
I already have an Audio 2, it's great for performing but the headphone amp is decent at best
and I've tried a Focusrite Saffire PRO 24 before which is around $300 for 4x6, wasn't impressed and the bundled software was messy