I recently got Shure SE846 IEMs which I'm connecting to a 2015 13' rMBP. The IEMs came with an inline volume attenuator, basically this.   At first I plugged them in without the attenuator and there was some hissing + high sensitivity to volume changes. I later learned both of these issues are...

Here's my setup: I have a JEC TC-716 stereo source selector (audio switcher). This switcher has 4 pair of RCA jacks and 2 stereo 3.5mm jacks. I use all four RCA jacks, one from my computer (which has a Realtek ALC889 audio chip), one from another computer in the room with the same specs, and one...