I initially did just that. Today I also turned off the surround as someone had suggested and that makes a big difference.

 

Thanx for replies guys. My ASL is on, surround off and it still sounds like crap in the back. Even if I adjust balance a bit to the back it still nowhere near what I'd expect from "LEXUS PREMIUM ..." or any other car system for that matter.
It just really sounds very weak in rear. At this point I just want to meet someone with RX and listen how it sounds in their car, I'm literally thinking there's something wrong with my rear speakers, that's the only way I can make sense out of that (lack of) sound.

 

What does sound like when you move the balance 100% to the rear speakers and leave all else in neutral??

 

In this case rear speakers work but defiantly not loud enough comparing to fronts when balance is in the middle. And most importantly there's zero "impact" or "feel" if you know what I mean. Speakers do work (produce sound) but as I mentioned before it's like they are not hooked up to an amplifier while fronts are. Reminded me of the days I used to play around with aftermarket speakers on older cars when you have rocking system all around but decide to not touch stock rear speakers so you can hear the difference between "awesome aftermarket set up and crappy oem" right away

 

My ML sound does seem to be louder at the front. This is something that should be fairly easy to measure and I'll make the attempt.

As for quality, it sounds kind of ordinary compared to the ultrasonic highs, earthquake-like lows, and thunderclap dynamic range of some systems, but I find the vocals are very clear and it's easy to listen to for long periods of time. Older recordings often seem monophonic, but newer ones can be awesome.

 

My balance is 2 clicks to the rear like others suggested and surround sound sucks. The front speakers should be louder, clearer, etc however when I turn off the front speakers the sound is not as dynamic but it still is a pleasant sound and I can turn it up to the point where it is way too loud.
However that's the ML system, there could be a much different result using the standard system therefore it would be more beneficial to you to have someone using the standard system to comment.

 

Sound quality is better than standard unit over all. XM radio issue is because it is based on satellite link.
Any audio system has to be set up properly initially like any other system like home stereo or home theater.

 

The numbers are in: If the reference level is the passenger front at 0 dBA, the right rear is -4.2 dBA. Roughly less than half the sound power, but due to ear's own level adjust, just noticeably less.
ML System.

Method:
1. Create a WMA file a 30 second frequency sweep logarithmically 20Hz to 20kHz place on USB stick.
2. Set sound controls to surround ON, volume balance/fader at center, flat frequency (default).
3. Record sound with Zoom H4N Pro audio recorder at stereo 44kHz sample rate and microphone set to 120degrees.
4. Analyze recording with Audacity and Wave Stats plug in.

Attach screen captures of Audacity. Not sure they will make it to post.

 

So is it better to have surround ON or OFF for the rear sound?

 

All I can say is that I love my RX but the ML system is absolutely horrible. Yes, the regular system is even worse, but I expected so much more with the ML. Just purchased an 18 XC90 for my wife with the Bowers&Wilkins and have to say, no comparison, they know how to make a truly awesome system in an SUV.

 

Definitely OFF for a comparison like this.

 

It depends whether the source material is encoded as 5.1 or 7.1 or 9.1 or 11.1 format.
If not, system will emulates surround mode. You folks should have home theater?
Ought to understand about Dolby, THX, Natural DTS, Atmos, stuff like that. If you play 2 channel stereo
material it won't produce real surround sound like sitting in a cinema. AVS forum is
a good place to learn about this things. If one wants to set up the system,pick a
good reference source material(usually Blue Ray disc) like good sound track
from a famous movie, etc.

 

Exactly, except the ML only decodes 5.1ch DD. The matrix "surround" mode setting is just a gimmick and actually degrades the audio. If you play a DD 5.1 DVD, it will play in surround mode with the setting disabled. I assume the test above was performed with a 2ch source. In any case, it will be much louder in the front, than the back by design.

 

Okay, same test with DSP off (maybe recorder positioned slightly different). The A-weighted sound in the back is -3.3dBA from the front. Just slightly louder.

Comments are correct. It's not the most scientific test, though reasonably repeatable if someone should do this with a premium system instead of ML. Possibly, the sound is biased towards the front to allow easier conversation in the back.

For reference, here are the new Audacity trace overlaid over the old.

 

You're all over-analyzing the sound in a car - it's not a home theatre. But do what works best for you.