The the output expander will not solve the solution. The effects in the ASR-10 works like this:
Assign an effect to the instrument, and that effect will sound only if the instrument channel is selected.
If the effect is combined (example: compression and chorus), those effects will be assigned to a bus individually. example: compression- bus 1, and chorus-bus 2, bus 3 dry.
Take notice that if an effect is assigned to instrument, the ASR programming will most likely keep bus 3 (dry).
If you buy the OEX-6 (it worth it if you track out alot), no effects will be assigned to the outputs of that expander.
If you have the cash and decide to invest in the OEX-6, look into the Ensoniq Dp-4.
Do a search for the Ensoniq Dp-4 on the web.