[Darryl Ramm]

128 channels at what sample rate? What computer? What connection?

Most interfaces only provide one coax MADI connector, if they have more it's likely optical and/or pluggable SFP. Which means you likely need at least one format converter (or more if running at high sample rates).

Got PCIe Slots? RME HDSPE MADI FX is the bee's knees.

At the other end RME Madiface do it for you? 64 channel optical + 64 channel coax = 128 channels at 44.1/48 kHz. Small compact. Low cost. USB 2 ... and RME has lots of stuff explain how USB 2 is fine for this IO count.

If you need two coax loops you could use a second Madiface in stand alone more to act as a format converter. Or buy a third party format converter. Or can you put an optical card/connection in the console? Esp. if going any distance I'd just rather run optical).

I have a Madiface (and Fireface UFX+), its nice. Typical RME quality, Totalmix mixer support. Has a limited stand alone capability to convert optical/coax. A Madiface is a handy tool to have with you if working with MADI even if it's not the main interface.

If you want more connectivity for other formats, then many of the RME interfaces have MADI on both optical and coax.

Other stuff out there from Moto and others.