For those willing to mess with the inconvenience of not being able to control your music from your steering wheel or stereo unit, I recommend trying out the
AudioQuest DragonFly Red digital-to-analog converter (DAC) / amplifier unit to complement your B&O sound system.
The DragonFly Red is a small USB headphone DAC / amp, but if you tether it to your mobile device and use the car's auxiliary input, there is a noticeable improvement in sound. It's essentially double-amping, but the benefit that's realized is via the unit's DAC section, which renders digital music better than your phone or stereo unit can.
That said, crappy recordings will sound crappy, but if you have well-recorded music or stream Tidal HiFi, it'll sound great. AudioQuest also makes the DragonFly Black, but in my experience, the Red is much better (and $100 more expensive).
