The MEC is one of the components of the late, lamented Ensoniq PARIS DAW system from the late 90's - early 2000's era. PARIS was highly thought of for it's converter and DSP sound quality (I know, I owned one for a long time), but it was a highly proprietary closed system, not just a 'sound card', and unfortunately, the system never caught on like it should have, IMHO, and it is long out of production.
The MEC is the chassis which contains the I/O for the PARIS system. There were slots for analog in cards, analog out cards, ADAT cards, and a time code synchronizer module. The rest of the PARIS system consisted of a PCI interface/DSP card for PC or Mac (you could use more than one to expand channel count), a single rack unit, simpler 4 I/O chassis for smaller systems, and a 16 fader/transport control remote panel.
There are a few remaining PARIS aficionados here: http://kerrygalloway.com/ParisForums/
You might advertise there for someone looking to expand their existing system.
I loved mine, the sound quality was superb, but software development stalled due to corporate mismanagement of the system... a sad story...