Over the past few months, I've been trying to get more and more into hifi gear, picking up a C421 headphone amp and a Fiio L9 so I could have a clean line out, as recommended by several members here.
Contrary to my expectations, I noticed that there was a significiant amount of hiss with the volume maxed out on the amp when plugged into the line out of my Nano 2G, even more so than when I was plugging via a regular 3.5mm to 3.5mm cable!
Thinking there might have been some issue with the amp, I sent it back to JDS for inspection, and was very well taken care of. I recently got the amp back, and noticed that hissing was greatly reduced using my home sound card (Xonar DX) into my GR06 and weirdly sensitive SRH440. I know the amp is supposed to have a black background, but I'm guessing the high sensitivity of those two would have something to do with it.
Anyway, I did some further testing on some other devices, an iPod Touch 2G and an iPhone 4S and noticed other issues with the line out cable.
The Touch has a weird crackling hiss going on when the volume is turned up on the amp, while the 4S starts with a static sound which goes away, but if I pause a song and turn up the volume on the amp, there is static present for some reason.
I know several members here claim that iPods with a good and some kind of LOD should produce little to no static with my IEMs. Am I just getting unlucky with the iPods I'm demoing, or could something be wrong with me LOD?
Thank for your thoughts!