Just thought I’d share this as I know quite a fewpeople now have the Xtrons stereo units. On the XDA Developers forum someone hasreleased a free update that dramatically improves the sound output from these headunits as somepeople don’t think the sound quality from theseunits is very good especially with Audis with Bose. I and another member on here have both got Boseand have both done this update and agree that it’sdefinately an improvement over how it comes out of the box. To do this update go on the android auto section of the XDA Developers website and look for a threadtitled (mod)(mcu)BD375xx sound processor. It involves no hardware modifications, it is simply anMCU update and installing a new amplifier app. The instructions are on the thread but you basicallyunzip the files on a computer/laptop and put themcu update and new amplifier app onto an sd card and then place into the gps/map slot on the unit andinstall the update and app and that is it. If you have a unit bought from Xtrons then you would do the GS mcu update, if you have a unit fromsomeone else like erisin or whatever then it’s upto you to find out which mcu update you need to do. The update is for android 6 and android 8 devices but if you have a different android version I’m surethere is a similar thread about the update for thosedevices. After doing this update your sound quality andespecially the bass will definitely be improved and if you use the new amplifier app you will have morecontrol over the sound settings.