Originally Posted by skootx
I have an update on this. I took a gamble on a $100 miniDSP, which is actually a VERY capable little piece of hardware. However, I still have massive hiss.
The miniDSP does some very cool stuff, by no means am I trashing their product. It's cheap, easy to configure with loads of forum/fan support. I'm a nutjob audiophile and for the price this little black box is amazing. The only trouble is, it doesn't do anything for the hiss coming from the head unit.
The bitTen gets rid of that hiss, right?
Not necessarily. But if you use the DRC for volume control, it will be a large improvement.
What was your method of integration? Speaker level into the miniDSP to get RCA level out?
If that's the case, make sure that these connections are being made as close to the source unit as possible. Once this is done, there are a few things that might be worth trying...
Solder an old, working RCA end to an old pair of earbuds. Since they're sensitive, you can plug them right into your miniDSP to listen for that hiss. If it is present at that point, there will likely be little you can do about it.
If the hiss is present during the earbud test, experiment with adding resistor loads to your speaker wire connections going into the miniDSP. If you can emulate similar resistance to what the head unit was receiving from the factory speakers, this may remedy the problem.
If the hiss is not present during the earbud test, consider using some heavily shielded RCA cables. They won't be cheap but they will help with the problem. Check out the EKS RCA Cables from KnuKoncepts. In addition to the heavily shielded RCA's, I would recommend bumping up your output voltage by adding a line driver directly after your miniDSP, before your RCA cable run. This builds off of what Steven said earlier in your thread about RCA levels being amplified along with the annoyances. If you start off with higher voltage before the RCA's pick up that interference from your cable route, the interference should be amplified less, making it less noticeable.
You can also experiment with using common grounding and power locations with your equipment. Sometimes something as simple as running a wire to connect grounds or power sources of the source unit, audio processors, and amplifiers together can remedy problems like this.
Take note that these recommendations are based on 'if's' and 'should's.' Troubleshooting and remedying engine noise and hiss with factory integration is almost always a guessing game.