no different than 9813 other than its a newer model and you can change colors & IT HAS 3 TEXT LINES INSTEAD OF 2. I say if you wanna save money stick w/the 9813.
9815 is a step above 9813 b/c the 15 has 3 lines and the color is blue.
TRUST ME if color isn't a big deal, stick w/the 9813
ALSO, i don't use internal amp.... as a matter of fact my brain tells my fingers to turn it off, so many years down the road when i decide to just have the hu and no amp, the hu will be like new b/c the power hasn't been used, lol VPOWER LMAO
i have the 9815 also, is there a way to turn off the internal amp or does it simply know not to use it if it doesnt detect a load on the speaker wires after you cut and tape them?
it should know seeing how u have rca's and remote wires goin to amp. but you can turn it off
hit setup button, which is hte button to the left of 1..... press and hold it
press the left or right arrow keys until it'll say somethin like pwr on..... hit the band button to turn it off. then press the setup button again and you're str8