Originally Posted by AntonP
I understand that Meridian's coax is only 2-channel, but Trifield works with 2-channels as I know. Is it function of DSP or 861 is needed?
Is a Meridian processor function, and covered the 861 user guide.

Originally Posted by AntonP
I got user manual for v4 but it is about settings, no wiring/connections frown
Maybe there is another manual, for the installer?
Not really, but check out the DSP speaker manual for examples of wiring Meridian digital theatre wiring illustrations.

Meridian's not plug a play, there is quite a steep learning curve which is not helped that Meridian manuals are well ... "not so intuitive" ... and required multiple reads before it start to sink in.
You not alone we've all been there, and there's lot's of advise here on the forum as well to help guide you.

Regards,
Carl

PS Analogue output cards for 861v4 do come up on the user market from time to time. However, there are quite hard to source these days.