I thought I would share a few pics of the USB HEC card I recently installed into my DSP.3. The process is dead easy - and took no more then 10 minutes. German engineering at its finest.
Yes, I know it says dsp.2 but I was assured by MSC that it was also compatible for my .3.
This is the entire package. A new face plate incorporating the added input, the HEC itself, a hex-key and a single hex screw.
Some DSP's unbolt the bottom plate, others the side plate (like mine). 4 phillips heads and a hex screw released the old face plate and allowed me to remove the bottom plate. FYI: I only needed to remove the one side, not both.
Slide the bottom all the way out, gently, and voila.
Simply take the HEC and plug it into the DSP board. Ensure that it is plugged all the way in. You don't need to crush it down but there is a little resistance to ensure a tight fit. As far as I can tell, it will only fit one way, so its a pretty obvious and easy to install properly.
Slide the bottom plate back into place. This will also let you know if the HEC has been plugged in all the way. As the lid will not slide back on without the needed clearance.
Attach the new side plate that came with your HEC card and you are in business. This really is a very easy little upgrade and now I can plug my phone or tablet or fiio or whatever directly into my DSP and help maximize the SQ in my vehicle.
Thanks for checking this out and hopefully it helps.