Not sure if this is the right forum to post this but I thought this might be relevant.
So basically, I have a new Galaxy S4, but it seems to have problems driving my Logitech UE600 earphones. Basically, when I set the volume above 50% to 75%, there is a noticeable 'crackling' sound in my audio, apparent mostly within the bass range. At first I was puzzled... but after reading this forum maybe I know why.
Based on the impedance graph I found here: http://www.innerfidelity.com/images/UltimateEarsUE600.pdf, it seems that my IEM's impedance goes below 10ohms until 1kHz where it increases. I suspect the S4 may be inadequate in supplying enough current at the bass range, causing noticeable crackling noises.
The S4 has no noticeable distortion when driving my ATH-M50 nor using its stock earphones.
So, do you think my hypothesis that the S4 is supplying insufficient current to my UE600 correct? Given the S3/Note 2 has an impedance of about 3ohms, perhaps the S4 has a similar high impedance rating.
In that case, would getting a portable amp theoretically solve the problem, if I connect it through the 3.5mm headphone jack? Or will there also be distortion on my portable amp, since the FiiO E7, for example, has an impedance rating of ~0.5ohms. In essence, would an amp amping an in-built amp solve the issue I am experiencing?