Reply to A&H Xone:42 + Traktor X1

Hello,

I would love to use and A&H Xone:42 Mixer, 2 Traktor X1 and an external soundcard to get the audio in the mixer.
My problem is, that i am searching for a soundcard with 8 outputs (4 stereo out) that is not too expensive but has an good audio quality and not that large latency. I found the Audio 8 and 10 by Native Instruments but they are quite expensive and you can only buy them in a bundle with the timecode things..
Do you have some advises for an audio interface with 8 outputs? Is firewire or usb better for djing? (latenzy, quality). Or should i look for some secondhand audio 10 interfaces?

Greets Lukas