My Zana Deux S has a problem that I can't figure out Various headphones with 1/4" TRS connections all work in other amps just fine but the ZDS only plays one channel at a time. Either right or left but not both. I insert the headphone plug, first the tip meets the sleeve and I get sound from the left channel. I insert it all the way and end up with sound just from the right channel. So the panel jack outputs left and right successfully. I think the amp connections must be good, right? I disassemble and insert a cable and I can see that mechanically, the connectors are behaving as they should. I test for continuity and it is there for left, right and ground, the plug and jack are mating correctly. So why can't I get both channels to play at the same time? The tip contacts in the right place, the sleeve and ground do as well. As I type this, I recall the Crack uses resistors between these 3 connections. I don't know about the ZDS. Any ideas?