"- you are able to control your volume with your headunit, while useing the digital in. so you donīt need a additional controller as the bitone needs it"
i dont see how that is possible, i havent heard of a headunit that has a variable digital output, in car audio. thats not how they work. a digital optical output is always the same no mater where the source volume is, the dsp will control the output volume on the analog side. thats the whole point of digital is just information in bit, no volume adjustments.
i dont understand how you could use the source units volume control to control the digital output unless the processor was hooked up to the analog also and was using the volume signal from the rca(analogy output) but using the actual audio from the digital output of the source unit, now thats a good idea, maybe thats it...