I have the 9833 and you should run the power wire to the battery. The ground should be grounded to the chassis, but I used the harness until I get some time to do it right. The current draw for the 9833 is more than the 9831. I used a 10awg amp wiring kit to run it to the battery. I love this deck.
I purchased a Rockford Fosgate brand 10awg wiring kit and I used the fuse that it came with. If I remember right there is also an inline fuse on back of the head unit. I used the one it came with as well.
One more question, if I connected a 10awg wire from the battery to the 16awg(?) from the 9833 harness, wouldn't the power be restriced since the wire goes from 10 to 16? (I'm guessing the awg from the hu is 16)
I was going over the same thing in my head at the time. It didn't seem to make sense. However when looking at how most amps are installed in cars most people use at least 4awg (I assume). The recomended size power wire for my amp is 4awg. However the amp only has an 8awg input. I ran it into a power dist. block and then stepped it down to 8. The same principle applies to the head unit amp. I soldered the two cables together and wrapped them in electrical tape.
As for speaker wire yes it is a power wire. However since not all the power is being sent to the speaker(s) at all times you can use a smaller size. My subs are wired with 12awg. You COULD use speaker wire as power if you didn't need a large gauge. The sugestion for using an amp wiring kit came from Crutchfield and numerous other trusted sources I found online. I figured it would be better to be safe than sorry. Basically speaker wire is the same wire used to plug you house lamps into electrical outlets.