I don't know if anything would be damaged by having multiple units connected to the minidsp, nor would I care to try and find out, just not a good way to go IMO (but then neither is having two systems like this). Just seems a waste of a $400 unit not being used but as a switch that you can buy for $20. Not sure you can even program the mindsp to function properly with each input separately....would have to dive into settings. Are you using one of these ddrc units?