Hello I have the 24 CHR with the JBL system. Tonically it works so reasonably. Only in the doors at the back it is as if there is nothing in it. If I fade back even my mobile phone is louder. I lack a bit of the “roominess” Besides, bass from the subwoofer is rather weak. Question: Has someone already replaced the speakers with others? Do I need a separate amplifier for it then? Merry Christmas Dietmarr