Lexicon MC-12

Just very recently sold my very very nice MC12B with all the accessories. I can tell you that a remote is highly desirable in setting up the unit. It can be done on front 
Panel (as far as I know) but it's nearly impossible and cumbersome in the extreme. I tried once and failed miserably. Just wanted to change a speaker distance. And i was very familiar with the menu and manual. In its day it was highly sophisticated and has many menu and setting levels. I do NOT recommend attempting to set up this unit from front panel you can really screw the pooch so to speak in a heartbeat. My suggestion to you is to find yourself a remote and read the entire manual at least 3X. Its a very thick manual. Use the OSD which will simplify you setup immensely. Once you accomplish that you'll be surprised by what this processor can do.
Hope this helps!

Also to reset the unit to factory settings is a 2 man operation unless you have very long fingers. If you need to reset I can give you the instructions on how to. It's not in the manual.

I'm not surprised that you are having connection issues as every input must be specifically set up individually and has 3 options, coax, opt and analog. If the input configuration is not how your source is connected you will not hear a thing. Same for video. As you can tell it has a lot of inputs so to happen on one that matches your connection is a crap shoot.  I cannot remember if the manual specifies the default setting for the inputs. If it does you may want to reset to factory settings and use the default connection.
Hope you get it working and happy listening.

Thank you gillatgh. Truth is, I was a little embarrassed to post that I cannot figure it out so your response is making me feel a little less like an idiot. This is a really complicated piece. It was thrown in on an amp so I have nothing invested but looks like it could reasonably capable- albeit if I can reprogram. 

If I can be of help feel free to pm. I'll do my best. I truly was impressed with the MC12B and only removed it from my system after a modernization. As soon as one friend heard he snatched it up. Never got a chance to list it for sale. I still have access to it when I visit him. He is planning to compare it to his Classe SP600.