Hi Buke9, I'm about to use 2.5 trrs and already have multimeter which I've used before to do 2.5 trrs balanced for HD600. 4-pin for JH is a bit different in compare to Sennheiser. There are 4 pins for: highs, mid, lows and ground as on picture bellow. It's not like simple HD600 signal and ground for each side. So I was wondering how to terminate all 4 wires on 2.5 trrs jack. Should I solder all three wires (high, mid and low) to signal for right and the same for left and ground as usual? Thanks all for any advice.