I know Alex had a dialog with the owner of WyWires to make an affordable solution. I believe it was for the RSA connector, but the TRRS is the same 4 wires so should be quite similar solution. But with all that's been said, the phase splitter works wonders. Don't be afraid to go that route. I haven't used a balanced input yet, and I'm in no hurry to do so.
5/23/16 at 2:36am