Cable diameter

Moin, a question to the electricians among you. From the battery to a possible distributor 50qmm2 copper cable. From the distributor to the subwoofer (15qmm2) and amplifier (25qmm2) each specially secured. From the distributor the two standard plus cables from the mini. Either 2 times 25qmm2 or 35qmm2, I do not know the exact cross-section. In my old table book I still found that you can load 16qmm2 with max. 65A. Therefore this would have to fit with 50qmm2 or lead a s ole configuration to problems?