Hello B László,
At a guess, you used an ASIO driver with your 7.1 sound card and RadioDJ. Possibly ASIO4ALL.
For reasons unknown to me, ASIO4ALL support stopped in PlayIt Live from 31 Aug 2016 (v184.108.40.2065).
If you use ASIO4ALL then a version before that, say
would be worth a try.
Other ASIO drivers work well in later versions but not ASIO4ALL.
I use a similar solution to you with PlayIt Live, I (now) have an ESI USB sound card (the U46DJ) for multiple channels of play it live.
I documented a previous setup with a 5.1 sound card (similar to your setup) at
You may find this of interest.
If you can provide more info on how the 7.1 sound card presents (in both RadioDJ and PlayIt Live) I may have further ideas.
What PlayIt Live can't do (sadly) is pick channels of a 5.1 or 7.1 card to send different players to. Without ASIO it seems to only see the first stereo pair from my experience.
Making long beds seems a good solution to your loop problem.