Yep, not positive on the 9886 but I have the 9887 and I believe they are almost identical.
Hold the Func./Setup button till the settings come up, go to GENERAL, then POWER IC, set it to off. That's how it is on the 9887 at least //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif.
my alpines amp can be turned off, if you switch it on/off you can notice a small difference but its not night and day... but why run the internal amp and have it generate power if you're not going to use it...