Weird. Not disputing your experience--how could I, I wasn't there!--but I owned a 2010 Fusion Sport for a couple of years, and I thought the Sony system was pretty good. Certainly better than the after market one I had in the old Focus ST I drove before that car.
Then again, I never ran it full blast I guess.
I'm 23 years old and my life revolves around music. I don't listen to music below 60% volume, period. I need loud, and I need quality. The ford wasn't so bad quality wise, but it was NOT loud, and the speakers still blew.