"If music is important to you"
Both my wife and #1 daughter are musicians (no, they both have day jobs, too!).
Several cars and years ago, I added an upmarket and aftermarket system to my wife's car. Her review of the sound was, in effect, "meh".
Since then I haven't bothered with car stereo upgrades. If they can't tell the difference, I sure can't. That said, my BMW's standard radio head has been replaced several times plus there have been several software upgrades under warranty. It's hard to imagine that HK's QC could be any worse.
E91 "Classic" BMW inline six, six-speed manual transmission, Alpine, Terra, Xenons, ZSP, ZCW, ZPP, PDC, CA, alarm, M shifter and M brake handle, Euro rear fog light switch, Euro aspheric mirrors, rear power outlets, Garmin nüvi custom cupholder mount, Lidatek, V-1 built-in remote display, tire pump, jack, floor mats.