Depends on what your hearing and goals are. In my case, I didn't want a large or heavy system, but wished for more accurate and clear music. I found it in my Z33 by upgrading my front speakers to MB Quart separates powered by a light and modest USB Amp under the passenger seat. After a few years, I wondered about the rear speakers and elected to try a pair of MB Quart coax back there. I'm happy to say, they sound great and add a bit of sound that does more than just rear fill.

 

One of the most often asked questions when it comes to the Z's audio. I have followed all past discussions and general consensus seems to be to invest in a good component speakers for the front and call it a day. However as said above personal preference plays a role as well . I have rear speakers but after years of experiments I finally decided to disconnect them

 

Next time you go to a concert , turn your back to the stage. Same answer.
But again everything is subjective , so do what makes you happy .