So I've got my X710BT working perfectly in my 2001 Lexus ES300. I'm having one final issue, and that is of background noise. It's in two stages and occurs even when audio is off. When the engine is off and the key is turned to "accessories" it's a very low level, barely audible hiss. If that was all I wouldn't mind much since you can barely hear it over the Avic's cooling fan. However, with the engine running the noise is much louder, more like a crackle. If the car is idling in park it's easy to hear, but on the highway it's barely audible over the road noise. I am using the stock speakers and amp, nothing changed other than adding the new x710bt headunit.

I have two ground loop isolators installed, one each for front and rear RCA outputs. I had limited car chassis around the unit so I had to fabricate a ground onto the car via a nut and screw for the ground on the cars harness, the avic's harness and the parking brake green/white wire (three grounds in total). Perhaps these ground are what's causing the noise, but then wouldn't the noise be the same regardless of whether or not the engine is running? I know some people bypass the stock amp and use the headunits internal amp instead. I'm not really interested in doing this since the amp seems to be ok with the unit when the engine isn't running (I don't mind the barely audible hiss, I can definitely tolerate it). I guess I'd like to get it to sound the way it does with the engine off when the engine is on. Any advice please post it, I'm lost here.

P.S. I know this is a very subjective question, but can anyone check on the upper, small speakers on each front door panel and tell me how loud they are in retrospect to the rest of the speakers? It sounds nuts but I can't tell if mine are producing sound or not when I have music playing, and I'm concerned that I somehow lost their functionality in the crossover to the new headunit, although I suspected they'd be taken care of with the front RCA left and right cables.

 

I can tell you the tweeters on the stock system get loud.

I was listening to a trance song with a lot of higher pitched vocals and you can clearly hear it.

Also, to try and isolate the problem, i suggest you physically cover the speakers with a rag on the pass. side and your hand on the drivers, listen to the song.

Then remove them [your hand & rag] and hear for a difference, if it sounds the same your highs aren't working, if there is a difference they are fine.

I know this is subjective, but it depends on the song as to how loud they are also, regardless of volume **** position. So try this out on the same song/same segment of the song.

 

Not a bad idea. Perhaps someone else whose done an aftermarket head unit can tell me if they were able to maintain the use of those small speakers, and if so how? I may hook back up the stock radio and see how they sound compared with the avic head unit.

Still looking into that hissing noise. If I don't gather any further info I'll play around with the grounds and if that doesn't work I'll just live with the noise.