Tanks for your answers so far!
>
>Oay, to make it more precise: I'm looking for an interconnect system
>(multi-channel plug + receptacle) for 24 differential pairs at signalin
>rates of 3 - 6 Gbps per channel.
>
That is an astonishingly high data rate (~70 Gbps to ~150 Gbps)! I won' ask what it's for, as I suspect you wouldn't be able to tell us. ;-)
How far is the system architecture defined? Instead of a 'Digital' board 'DAC' board, could you do it with a series of 'Digital + DAC' slices, eve if that meant replicating some of the functions in each slice?
On a previous project, the high potential interconnection data rate rendered the 'obvious' approach non-viable, and so a mor communication-friendly architecture had to be developed.