Which smartphone has the best bluetooth sound?

...is strictly sound quality. And the reason why I mentioned the "premium sound" is this - there are 2 cars in my household, one with premium sound and the other one without. The sound deficiencies don't show in the "regular" sound car but they do in the premium. Any sound system will expose more sound deficiencies the better the system is.

Thanks for the reply!

...this is not a sales person speech; it is my own experience. I am not disputing the fact that a standard is a standard, but there is a difference, I hope you trust me on this. I am meticulous with sound. I am no expert in the matter and that's why I'm reaching out, but there is a difference. I know BT is a standard, but then there are differences in the AVRCP version, for instance? I know that when Android 4.3 was released it brought along a newer version of AVRCP and I hoped that this would "magically" fix the issue, but it didn't...

Let's look at AVRCP again.
https://developer.bluetooth.org/TechnologyOverview/Pages/AVRCP.aspx

It's a standard and no one can improve that area. Sure you may find a bad implementation but that's not the question.

Here's my answer. Forget BT Audio and BT "profiles" but move to something that moves the audio file to the device and commands it to play. Then you'll get whatever that device can deliver without limitations of BT Audio standards.
Bob

I don't get your proposed solution to circumvent limitations imposed by the BT audio standard. Would you please elaborate? Thanks a ton!

...but I don't see how I can implement this with my car audio. Quite frankly, I would connect the USB and be done with it, but when I do I get an error in the car audio system. My stupid car plays better with iProducts, if I plug an iPhone to the USB connection I can control de music through the car system. Still not enough to sell me on Apple products though, if that's what you were thinking.

Why not try again and supply full details. Now that we know it's a car, maybe folk can comment?
Bob

Sorry that it wasn't clear anyway. Is there any otherIt's a formation that could be useful? It's a Subaru Outback with the Harman Kardon system.

I didn't see a specific solution yet online, but in many cases, if the head unit isn't updated, you might be SOL with some phones IME.

Example from forum:
http://www.subaruoutback.org/forums/80-electrical-electronics/74490-help-bluetooth-audio.html

The fact that Android OS & associated hardware is so fragmented does little to help overall compatibility unfortunately .

...to see if there was an update, but I never did as I never hoped that an update would fix the audio issue.

In the forum that you linked, somebody was saying that when playing from an iPhone all the info was displayed on the screen, but that went away on the update to iOS7 (that post is from June 2013). Not that I care, really. I mean - yes, it bugs me to not have the info on the display and having to pick up the phone to see the name of the song, but I'll worry about that once the sound problem is gone.

...very well may have already been addressed/fixed in the subsequent iOS updates since it was first rolled out. Often the forum threads do not reflect the updated technical fixes. I also wouldn't rule out HK either as a partially guilty party. YMMV.

...I read in many places that BT will give you the best audio quality out of all the options out there. The sound quality is definitely better on BT than through regular 3.5 mm audio jack - the AUX audio has a background hissing (reminiscent of the cassette tapes!) and the cymbals are rather dull; through BT the hissing is not there and the cymbals are crisp. But I can't speak of the USB option as it didn't work through a cable.

I will try putting music on a USB drive and plugging that in tonight on the way home to see how it does. The tree structure would be artist name / album name / tracks, so 3 layers.

Headphone audio output to BT isn't a good comparison, since it's common knowledge that headphone output is not ideal. You should be comparing BT to a wired, digital connection via the dock connector on your device. This is always better than BT *IF* implemented correctly (which in your case, it may not be).

Apple has worked hard to make the sound quality quite good in this arena. Since the Android OS & (multiple) associated hardware is so fragmented, it's not as easy of an issue to deal with QC-wise IME. It can take quite a lot of futzing.

In regards to your statement "You should be comparing BT to a wired, digital connection via the dock connector on your device." - I connected the phone through the micro USB port using a USB cord to the USB jack on the car, and I get an error on the head unit, it can't read it.

I plugged a flash drive straight on the jack last night. The result? Yes, it sounds great; yes, all the track info is on the screen. But... no folder structure whatsoever, albums not even in any particular order. Here's what I put on my flash drive (in alphabetical order, which is how they appear on any device):

Chastain
2013 Surrender To No One

Dream Theater
1992 Images and Words
2007 Systematic Chaos
2013 Dream Theater

Pantera
1992 Vulgar Display of Power

...and then inside each folder there are the tracks.

Here's what the Head unit showed:
1992 Vulgar Display of Power
2013 Surrender To No One
1992 Images and Words
2007 Systematic Chaos
2013 Dream Theater

So they were not in order by album name, not by year of release (since I put the year of release ahead of the album the order should be the same) not by artist (it was Pantera / Chastain / Dream Theater).

Imagine trying to navigate my 300+ CDs if they are not in order...

You might search around to see if there are any MP3 file naming conventions you could try as valid substitutes. Personally, I would dump the year in front of your files to see if that helps at all.

Dimebag Darrell is likely responsible for all other issues