I have noticed on some S+ modues where Threadsafe logic has been added in and they are using the #IF_SERIES3 directive, that when you compile the S+ with 4 series checked it will throw an error?"Logic excluded as a result of #IF_SERIES3 directive"?when compiling for 4 series- it does not like the #IF_SERIES3 directive. So to me that means at runtime it is not using any of the Threadsafe logic contained in that IF statement, and is instead running the ELSE logic- which may be detrimental to your desired operation. I personally saw it with a Marantz SR-7007 module. I had to resort to changing the logic to #IF_SERIES2 and #ELSE (threadsafe logic) which seemed to do the trick. But if we have to open up every S+ module and do this its gonna suck. And the fact that Simpl doesnt warn you of this when you do a recompile all you have no idea it may be broken. Still waiting on TB to tell me if Threadsafe is no longer needed for 4 series.?
Not saying this is your issue, but something to think about. Although it seems others do have it working so I may just be babbling here haha?