Look at RME if it's audio recording. Also, is scalable to a degree.

www.rme-audio.com

This might be pricey though.

That's a lot of channels. What's your budget? You might need a custom engineered solution or if you don't have a budget do it yourself. Did I say that's a lot of channels? That's a lot of channels. For how long are you wanting to record? 5kHz is not much but x 480 x 60 seconds... the data starts building up fast.

Have you looked at National Instruments PXI solutions? A single PXI card could capture (16 differential / 32 single ended) at 16 bit, 1 MS/s. Gang together a couple of chassis with several cards would fit your request, however the cost is going to be in excess of $20k for 480 se channels with this particular setup. Lower resolution with slower sampling rates are available at lower cost, but would probably still be in excess of $10K. There is a plus side to this solution though, expandability. This system could be adapted to almost any future requirement.