Dude,
The Pros and Cons of these 2 units are very similar.
Ive got the Firebox and an Audio 8 (which is just a bigger Audio 4).
Can i assume your using Traktor? If not what im gonna say is rubbish?
The first question are you ever likely to use timecode ? If the answer is “hmm maybe” then dont bother with the Firebox. You need the A4 for timecode (despite what you may be reading at the moment) if your serious about DJing and may use timecode in the future you need an N.I. card.
Both cards are similar spec and sound very much alike. I would say the the Firebox is a tad louder , dunno why it just is.
If you arent gonna use timecode then the main and probably crucial difference is that the Firebox is FireWire. Have you got a FireWire input because no matter what anyone will tell you FireWire gives you total piece of mind. Zero latency, and a connection that isnt troublesome or delicate. You dont get USB errors with firewire (obviously).
The Audio 4 is a very durable tough card but the Firebox is made from molten iron extracted from the heart of a star. It is the most solid piece of kit i have ever seen, Seriously , i have thrown mine in by gig bag and around DJ booths like a football. Ive seen the Skate vids for the Audio 4 so i guess its also very strong.
The Audio 4 has standard RCA outputs. The Firebox uses 1/4 inch jacks so you will probably need to bodge some leads together but thats not a real problem.
The Firebox has Midi in via spdif connection (you get the lead in the box). Very handy for contollers.
The Audio 4 has no Midi connection. And powers by USB
The firebox (depending on your laptop) needs the power adapter to jump start ( you can disconect when its started but why bother, just power it from the mains).
The Firebox has 2 firewire outputs.
The audio 4 has no mic inputs, the Firebox has 2.
Overall the A4 is a great soundcard for 2 channel timecode setups or 4 internal channels.
The Firebox is the perfect card for non-timecode use.
You wont regret buying either card, but personally if you are never gonna use timecode, get the Firebox.
Hope that doesnt muddy the water even more.