I would love to back something like this, but I have a few questions.
1. Why are all the head unit manufacturers still using old Rockchip and Allwinner CPUs that only support up to 4.4.x? Why not choose a more modern chipset that will run Lollipop (or even, should I dare, Marshmallow)? It's 2015, and to come out the gate with an old chipset that only runs Kit Kat is rather disappointing.
I think this is because development of Android head unit is not that easy. The process takes longer time than mobile phones and tablets which normally come from IC vendor's reference design, maybe turn-key solution. Android head unit development team needs to handle more tech issues which are not found in mobile phones and tablets. Developers are also lack due to attraction of mobile phone industry. Market size of Android Head unit is maybe 1% of Android phone's.
Good news is, in our OctaCore(2GB DDR) solution, porting of Lollipop is in progress.
2. Closed-source MCU is really the downfall of these head units. I've owned a couple of different types, and the MCU is always the weakest link. The Newsmy doesn't support audio mixing (no EQ) without software EQ, the HuiFei and clones don't support the EQ using FM or auxiliary inputs, and capped "shut-down" times are extremely annoying. Why not do the same as locking the screen and put the device in a lower power mode? The Newsmy community at least worked around this with xdAuto ROMs that allow up to 2 days standby, but that's only because someone at Newsmy posted the ROM source accidentally. Some still have wake issues, etc that would be easily resolved if the MCU were open source.
Open MCU is a bit hard. Firstly, it is normally based on a particular development platform with NDA and in-house tools. Secondly, MCU software is very much connected to hardware control which must be handled very carefully. Thirdly, even you have source, sometimes you may not build a bin if lack of tools and documents.
Doing shutdown in stead of sleep mode is a safer choice than running out of one's old battery and you may not start car next morning. In fact, it is also the industry's choice even in aftermarket. Local distributors in many countries demand <5mA power consuming when acc off.
3. Will this have pre-amp outputs for external amplifiers? A separate channel for subwoofer that doesn't send all audio frequencies? Front and rear pre-amp outs?
pre-amp output is there with a wire for subwoofer.
If these things were addressed, I'd highly consider backing a project like this. But especially without open source MCU, those of us who have experience with other units would be very hesitant. Designing a new product in 2015 that's capped at Kit Kat from old 2012-2013ish chipsets don't help move things forward either.