Reply to Sound Interface

So I just picked up a pair of KRK Rokit 8 monitors today and I was wondering what Sound Interface I should pick up to use with them? I would prefer to use firewire but it'd not really a deal breaker. Also I'm not sure which type of cables are higher quality but obviously with monitors this nice I'm fine spending a few extra shillings to get full use of the monitors. I was considering the Echo Audiofire 2, seemed nice and simple. I could use my monitors through the 1/4" jacks and even plug in some headphones. My other option is the Presonus Firestudio Mobile. I'm not getting I firebox though because I hear the levels are super quiet.