Premium sound speaker upgrades?

[drod]

I made the mistake of not getting the premium sound with my 08.. and ultimately went through a tedious upgrade project which included swapping out the OEM speakers to Polk Audios and adding a second amp.

the load is now balanced between two amps..

the sound is obviously much better than stock but it didn't really give me the true surround sound feeling I was looking for...(like it needed more speakers)

I never did like the idea of only having one central speaker in the dash..(when most vehicles have left and right, in addition to the ones on the doors)

I did however have limited options since my goal was to keep things looking stock...with no boom boxes in the trunk or oversized speakers mounted anywhere...

compared to the BMW factory stock system, the premium sound pkg comes with slightly upgraded speakers, additional speakers in the rear of the cabin and a 600 watt 9 channel amp.

I am making a new X5 purchase soon and was wondering if adding the premium sound pkg makes a huge difference or should I stick to the stock system and perform another upgrade...(obviously with a different solution)

maybe getting the premium sound and just upgrading the stock speakers to better quality speakers may be the best way to go...(kind of like the best of both worlds...)

thoughts??