washed out sound rcd510dab

I know the roomster is not the ideal soundscape

I recently changed the std swing unit for a rcd510dab from what looks like a beetle (thats the back end picture I get when I select reverse)

I seem to have to turn it up rather loud beyond halfway to get it fairly loud enough to hear (swing was at 8 on the volume before it was too loud ) and it had virtually no bass

I read somewhere it might be coded to accept the vw amplifier but I assumed I would get no sound if that was the case

I've droped the MIDs and the treble eq down and the bass up bit still sounds washed out