I never had this problem. Did you hear the distortion too, when you connect headphones to your player? I mean is it definitely not a problem of the amp? A possibility could be that your files are tagged with positive (wrong) replaygain tags, this could lead to distortion because rockbox can apply replaygain. There is also a "compressor" software effect that could be switched on accidentally.
Extract the content of a zipped theme to your DX50. You should find a directory named "rockbox". A difference between a regular rockbox build and the DX50 build is that the folder in the zip file is named ".rockbox" and the one on the DX50 is called "rockbox" (without dot). So just extract the content of the subfolder ".rockbox" to your DX50's folder "rockbox" (folder "theme", "wps",...) .
Take themes for Cowon D2 because it has the same resolution an also a touchscreen: http://themes.rockbox.org/index.php?target=cowond2
To flash a new firmware version you have to flash "stock recovery" in CWM (included in the Mod-Package of DOC2008: http://yadi.sk/d/UbPDGP_IKvVCA) first. Then boot to stock recovery and apply the update with the stock recovery.
To be able to use rockbox again, someone will have to build a new firmware file containing the new firmware AND clockworkmod recovery. I'm quite sure that this will happen very quickly after a new release.
thanks for the fast reply.
Not sure how to quote single parts of a post yet... o_O so everything in one.
For the distortion. No that's the thing. Sound is perfectly fine wherever I plug it in to, except for the car line in. Tried multiple headphones and stereo systems at home and everything is perfectly fine. Maybe I will try to lower the replaygain (I saw it was activated by standard by rockbox) and check for the compressor you mentioned
Really bugs me, since like I mentioned for about 50 % of my songs the sound is great.
Just tried to install a new theme and it works :D
The only "problem" now is that I can only select this one theme and the ones that were installed already in the standard package cannot be selected anymore....strange, but I got my big album art theme now :)
And for the firmware...oh I already thought I might have go back to stock recovery for this...guess I will wait then for the updated rockbox file before doing this. Usb DAC is just nice to have anyway for me and not super urgent.
One other thing, where can I buy a longer coax cable for dx50? my coax connection at home is on the back of my system, so the cable is muuuch to short. I couldn't find any place to buy such a cable,especially since I'm not even sure what exactly I have to look for...