I don't know why these are so rare, but it's next to impossible to find any double-DIN head units with Toslink output.
I've been doing random Google searches from time to time over the past couple of months, and other than one or two Clarion head units and some off-brand Android head units, it seems that no one else on the planet make head units with an optical output. Alpine apparently made one a while back, but it was discontinued.
This makes no sense to me considering any decent DSP or DSP amp comes with a Toslink input. The fact that when running Toslink, you no longer have to worry about line drivers for upping the line level voltage, no noise getting injected into the system, and only a single "cable" running to the rear of the vehicle to deliver the source signal to your DSP/amp.
Since I'm designing a totally new system for my up and coming 2001 Lexus LS430, and I now have a Helix DSP.2 which has a Toslink input, I would much rather utilize that rather than running interconnects through the car. That way I would only need very short interconnects between the DSP and the amps.
Then again, I could go one step further and remove ALL of the interconnects from the system by selling the Helix and getting something like the Zapco ADSP-Z8 IV-8 amp with built-in DSP and 8 channels of amplification to power the entire system, including the sub(s). <-- A very VERY good solution for a clean, stealth, low powered SQ system.
This car is SO quiet inside, even at 80 mph on the highway, you don't need a lot of power at all to get decent clean sound.
So with that said, am I missing something here or are none of the popular audio brands really not producing head units with Toslink outputs?