Ummm....your TRRS cables should have 4 conductor TRRS plugs already, no? The 901 already has the correct TRRS 4 conductor jack, so why would you need an adapter? If your cables are really just the 'normal' stereo 3 conductor plugs then you must re-fit them with 4 conductor TRRS plugs and then you are good to go. You cannot convert a stereo 3 conductor plug/cable to 4 a conductor balanced cable with just an adapter. The signal lines must stay isolated (independent) all the way from drivers to the plug with no merged ground connection which is what 'normal' stereo 3 conductor plug/cables have.