Started experimenting today with one of these:
It has an optical out which Iíve fed directly into the DSP, bypassing the stock HU all together. From a quick test it sounds nice and crisp as you would expect; Iím sure itís an improvement on the stock HU, however hard to tell by how much without comparing at the same time.
1) It has a battery which last 25Hrs (according to the website) but needs to be charged. It charges off USB so needs 5V. I could use a cigarette adapter but that sounds messy. After it shuts down due to low battery, I assume it doesnít turn itself on again automatically when connected to power. As it really needs to be in the boot where the DSP is, thatís a problem. If it is to be a permanent, I might need to build a little relay circuit which switches on a USB power supply, then after a short period of time switches the unit on.
2) As it bypasses the head unit, you have to tell the DSP to switch source from HL in to Optical in. The DSPs remote keypad is in the glove box so that isnít convenient. Might need to move that if this is permanent.
3) Bypassing the HU means no speed cameral alerts, and no sat nave audio (I use google maps anyway) - I can live with that
4) Volume can only be controlled on the source device; in this case my phone. Limited to the 16 volume increments. Not ideal, but I can probably live with that.
Havenít decided if it will be a permanent fixture yet, but it is fun to experiment.