Are any passive (or active - unlikely) components used in the 3.5mm mini stereo headphone (TRS) plug to RCA audio plug converter cables, such as [this one](http://www.amazon.co.uk/3-5mm-Phono-Stereo-Audio-Cable/dp/B000Q6LSVS/ref=pd_sim_sbs_ce_1) ?

Asking because, during a quick search I came accross some DIY cable post, where a poster commented that they find the audio volume to be extremely low when using such a cable, indicating serious attenuation. 

For line-in/line-out (on PC), I found the following [Wikipedia entry](http://en.wikipedia.org/wiki/Line_level#Line_out) that talk of the electrical characteristics, but nothing (so far) for RCA audio connectors and the 3.5" mini (TRS) headphone plug.

Also found this interesting [post](http://en.wikipedia.org/wiki/Line_level#Line_out), but it is in reference to RCA to SPDIF conversion (chain), but still not much helpful with respect to my question.