I have two of these units, my only problem I found on the two units I have if you play cd's while plugged in with the adapter you get a lot of swishing noise interference and if you play CD's via Battery or Mains anything recorded over 86db shop purchased or ripped sound is distorted at any volume level also because the usb reader is connected and controlled by the same cd electronics I also found tracks recorded at 86db are also distorted. the aux sockets at the side for input are good if you can control the volume levels from the source going in (example headphone socket to Aux, using volume level from source device) I found sound distorts from Aux to Aux on some devices that you cant control the volume in.
I thought there maybe a internal line in audio level controller on the circuit board and may be set too high at factory, I couldn't find one.
Its very Strange that two units would be like this, I suggest anyone buying one to walk in the shop, physically ask them to take it out the box and play a few different CD/Mp3 discs to see and inspect the units, the first one I purchased had a screw from the speaker rattling around in it and the second unit one of the antennas was loose because the screw supposed to be holding it firm was non existent so I think their quality control is not that great.
I'm not saying all units will be like this, maybe I have been unfortunate, but like I said take out the box in shop and try before you buy.
so for me to get round the distorted Cd problems is to rip CDs/mp3 disks at normalisation of 84db also do the same for mp3 files on the USB
if anyone is interested recording from cd, tape , radio, aux, to USB the unit records only at 128Kbps and can not be changed.