I used to work for Dolby - and know a bit about audio - and I'm in exactly the same dilemma as you. I'm buying a 328i convertible - so not quite identical, but close. Today I just went in and compared the stock and HK stereos.
- the stock stereo is very decent indeed (compared to stock Honda)
- the HK goes louder and is slightly crisper/clearer
- however I have to say the bass was still not as impressive as the 240W system with subwoofer that came stock in my current Honda Civic Si. I don't think you're getting anything beyond midrange units and tweeters based on the HK spec.
My own verdict is that I am going to go with the stock stereo.
I can also speak to "surround sound" with authority on the topic - worked on that (as a marketer) at Dolby Laboratores. Almost 99.999% of music you buy / download / stream from services like Spotify is in stereo, period. There are some very few exceptions of genuine multichannel (multichannel=5.1 or more channels) and to play this back you need a special head unit seen only rarely in I believe Acuras that plays 5.1 channel audio DVDs (rarer than vinyl). So what you will get is "matrix surround" - the chip simulates putting things to the back and front based on guesswork - but don't be deluded that this is "how the musician intended", simply a computer simulation.
Based on consumer research and listening tests, the biggest improvement in perceived sound quality from technology comes not from surround (which can score the same or worse than stereo for many consumers as it is unfamiliar) but *dynamic equalization*. Switch this on and everything sounds much crisper and clearer (it goes to 11). This is where we saw scores really jump big time.
Dynamic equalization is like graphic equalization, only intelligent. It "smooths" audio to an optimal equalization curve. If at any moment there's enough bass at say 300 Hz to match the optimum it lays off (while a dumb graphic equalizer will still boost), same for other frequencies. If there's too little at say 10KHz it subtly boosts this until matches the optimum equalization curve.
The bad news is that dynamic equalization is not yet offered by Dolby for car stereos. There are a number of equivalents offered by Dolby's peers (Beats), but IMHO (and others) Dolby's is superior - or at least was 6 months ago.
The good news this Dolby dynamic equalization technology (Dolby Home Theater v4 and Dolby Advanced Audio) is starting to appear in devices such as smartphones and tablets, so you can pipe it in via your AUX IN. These Dolby "post processing" technologies also matrix upmix - but remember there's only a stereo in jack in most cars, and even with the USB you're not going to get 5.1 from your Android device to your car stereo, so any upmixing beyond stereo can only done by the car stereo itself.
One might also mention that iPhones already have some basic tuning and optimization - but we're not talking dynamic equalization.
328i convertible | Deep Sea Blue | Black / Dark Walnut
Last edited by ixsomerset; 01-17-2013 at 03:07 PM.
Reason: Verdict added.