I have the JH13 as well and use it with my GO1000 often.. what you're hearing out of the port labeled 0.47 ohm is what I hear from my 47 ohm port. It looks like the impedance labels were switched on your GO. On my GO, the 0.47 ohm output is on the side of the volume buttons.
Yeah, my .47 is on the volume button too. But the bass bleeds into everything out of the .47. With the 47 out, it's controlled and tight. I think it got reversed somehow. Go figure.