Sound quality difference between BT and USB?

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2017 Mazda CX-5 GS
Is there any difference in sound quality between using my iPhone through BT or through the USB cable? I can’t tell any difference, but I thought some of you audiophiles might.
 
Solution
I normally use BT just for the convenience, but decided to give the USB connection a try. To my ears, in a moving vehicle, especially with snow tires, the difference was negligible. But the technology explanations make sense. I’ll keep experimenting. Thanks for all the articles.
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2019 CX-5 GTR
PLENTY of conversation around which technology is "audio superior"




https://www.reddit.com/r/CarAV/comments/8ra9zz



I don't want to ruin the surprise.. so report back with what you found out.
 
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2017 Mazda CX-5 GS
I normally use BT just for the convenience, but decided to give the USB connection a try. To my ears, in a moving vehicle, especially with snow tires, the difference was negligible. But the technology explanations make sense. I’ll keep experimenting. Thanks for all the articles.
 
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Solution
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South Carolina
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12 MZ5 13 CX-5
USB and Bluetooth are simply ways to deliver a music file.

Now, that said, whatever you do, don't ever use an mp3 file for anything. There was a time and a place 25 years ago when mp3 sorta kinda made sense, back when we had 56kbps dial up modems and 700 megabyte CD-R's, because thumb drives didn't exist yet. But dial up modems and CD-R's have died and been surpassed, and mp3 should have died along with them. With 100Mpbs internet speeds and thumbdrives the size of a dime that can hold 512 gigabytes of data, you cannot come up with a single valid reason to still be listening to horrific mp3's in the 21st Century. Load up a bunch of wav or flac files on a thumbdrive, and listen away!

Now, notice I said use USB. Notice I didn't say Bluetooth. Why? Because the theoretical maximum file transfer speed of one very specific high end and expensive piece of Sony Bluetooth hardware is 990kbps. For standard Bluetooth that most people think of, like a phone to a car stereo, the maximum theoretical limit is 576kbps. In real world, it often dips down to 256kbps, or even lower. Compare that to the sustained bitrate of a regular old CD at 1,411.2kbps. Surely you can see that there's something major lost in translation there. When you play a wav or flac file off of a thumbdrive, you are playing the exact same signal that is contained on that 1,411.2kbps file that's on a CD. There is no bluetooth in existence that can handle a the unaltered signal of a real CD. The technology simply doesn't exist, even with the high end Sony stuff.

If you say that you can't tell the difference between listening to an mp3 via bluetooth vs a real CD, then you're stone deaf, have an utterly garbage stereo, or both.
 
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2017 Mazda CX-5 GS
USB and Bluetooth are simply ways to deliver a music file.

Now, that said, whatever you do, don't ever use an mp3 file for anything. There was a time and a place 25 years ago when mp3 sorta kinda made sense, back when we had 56kbps dial up modems and 700 megabyte CD-R's, because thumb drives didn't exist yet. But dial up modems and CD-R's have died and been surpassed, and mp3 should have died along with them. With 100Mpbs internet speeds and thumbdrives the size of a dime that can hold 512 gigabytes of data, you cannot come up with a single valid reason to still be listening to horrific mp3's in the 21st Century. Load up a bunch of wav or flac files on a thumbdrive, and listen away!

Now, notice I said use USB. Notice I didn't say Bluetooth. Why? Because the theoretical maximum file transfer speed of one very specific high end and expensive piece of Sony Bluetooth hardware is 990kbps. For standard Bluetooth that most people think of, like a phone to a car stereo, the maximum theoretical limit is 576kbps. In real world, it often dips down to 256kbps, or even lower. Compare that to the sustained bitrate of a regular old CD at 1,411.2kbps. Surely you can see that there's something major lost in translation there. When you play a wav or flac file off of a thumbdrive, you are playing the exact same signal that is contained on that 1,411.2kbps file that's on a CD. There is no bluetooth in existence that can handle a the unaltered signal of a real CD. The technology simply doesn't exist, even with the high end Sony stuff.

If you say that you can't tell the difference between listening to an mp3 via bluetooth vs a real CD, then you're stone deaf, have an utterly garbage stereo, or both.
Actually, I didn’t say anything about an mp3, a thumb drive, or a CD. I’m referring to an iPhone streaming Amazon Music, or playing from iTunes maybe, either through BT or the USB connection. The USB connection does sound better, it’s just not a huge deal to me. However, I appreciate the diagnosis, it will save me a trip to the audiologist.
 
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South Carolina
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12 MZ5 13 CX-5
Streaming, except for Tidal or Amazon HD, is even worse than mp3. So right back to what I said: avoid bluetooth, use USB.
 
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2017 Mazda CX-5 GS
Streaming, except for Tidal or Amazon HD, is even worse than mp3. So right back to what I said: avoid bluetooth, use USB.
Yeah, this is the first time I’ve tried any of the streaming services. I usually listen to podcasts or audio books these days, and have just recently wanted to listen to a little music. In search of some variety beyond my own music library, I tried Amazon. The quality is terrible. Even I noticed that. It is somewhat better with the USB, so I’ve been using that. It’s all pretty good compared to BT streaming into my motorcycle helmet speakers going down the road at 65, so I’m pretty easy to please.
 
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South Carolina
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12 MZ5 13 CX-5
To be fair, I use Pandora via Bluetooth in my garage on my shop radio, or on my computer while I'm at work. But that's just for background noise while I'm working. :) So yeah, streaming definitely has its usefulness. I'd never try to use that crap in my car though.
 
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2019 CX-5 Signature
Yeah, this is the first time I’ve tried any of the streaming services. I usually listen to podcasts or audio books these days, and have just recently wanted to listen to a little music. In search of some variety beyond my own music library, I tried Amazon. The quality is terrible. Even I noticed that. It is somewhat better with the USB, so I’ve been using that. It’s all pretty good compared to BT streaming into my motorcycle helmet speakers going down the road at 65, so I’m pretty easy to please.
Just use MP3 encoded at 256, or 320kbps. In the CX-5, you will not be able to differentiate between CD quality and higher bit rate MP3. The audio system in the CX-5 is the weak link here.
 
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South Carolina
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12 MZ5 13 CX-5
Just use MP3 encoded at 256, or 320kbps. In the CX-5, you will not be able to differentiate between CD quality and higher bit rate MP3. The audio system in the CX-5 is the weak link here.
I definitely disagree. Right this second, I have a very mildly upgraded stereo, a Kenwood DDX8905S and a pair of $45 Rockford Fosgate Prime 6.5's in the doors. No amp, stock speakers in the back doors.

The difference between mp3 and flac is absolutely obvious.

I'll soon be installing Linear Power amps and component speakers though. That's when things are really going to start getting good. :)
 
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2019 CX-5 Signature
I definitely disagree. Right this second, I have a very mildly upgraded stereo, a Kenwood DDX8905S and a pair of $45 Rockford Fosgate Prime 6.5's in the doors. No amp, stock speakers in the back doors.

The difference between mp3 and flac is absolutely obvious.

I'll soon be installing Linear Power amps and component speakers though. That's when things are really going to start getting good. :)
I'm not sure how you can disagree, since you are not running a factory setup. You clearly felt the need to upgrade, so there is no comparison.
 
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South Carolina
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12 MZ5 13 CX-5
The reason I wanted to upgrade is, the factory unit doesn't play flac or wav files. Other than that, I would have kept it, because the CD player sounded terrific even with the factory speakers. Way better than playing any mp3. I went ahead with that particular Kenwood I got because it also had Android Auto, which is great for Waze integration, it uses the iDataLink Maestro RR which gives me real gauges, plus it has HDRadio built in. If I was going to spend money to get a new stereo, I was going to get one that had everything.
 
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2019 CX-5 Signature
The reason I wanted to upgrade is, the factory unit doesn't play flac or wav files. Other than that, I would have kept it, because the CD player sounded terrific even with the factory speakers. Way better than playing any mp3. I went ahead with that particular Kenwood I got because it also had Android Auto, which is great for Waze integration, it uses the iDataLink Maestro RR which gives me real gauges, plus it has HDRadio built in. If I was going to spend money to get a new stereo, I was going to get one that had everything.
The only way your CD sounded better, is if you had a poor quality MP3 master, or your audio settings were different between the two sources. There is nothing terrific about the factory sound system in the CX-5. It is adequate, at best. Similar to a Blose cube speaker set-up.
 
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sm1ke

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Canada
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'18 CX-9 Signature
The reason I wanted to upgrade is, the factory unit doesn't play flac or wav files. Other than that, I would have kept it, because the CD player sounded terrific even with the factory speakers. Way better than playing any mp3. I went ahead with that particular Kenwood I got because it also had Android Auto, which is great for Waze integration, it uses the iDataLink Maestro RR which gives me real gauges, plus it has HDRadio built in. If I was going to spend money to get a new stereo, I was going to get one that had everything.

The point is that while the difference in audio quality is there, whether a layperson would be able to hear a noticeable difference depends on the audio system. With the factory Bose system, you probably wouldn't hear much of an improvement because you're limited to the capability of the factory system. In an upgraded system like yours, the audio quality improvement is much more apparent because you have a more capable system.

Basically - USB can make a noticeable difference, if the source file is good quality and the audio system is capable enough. Assuming @Jnclem has the CX-5's factory Bose system, his initial comment that he can't tell a difference is enough to illustrate that there is no difference between bluetooth or USB for the audio file format he is using.
 
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South Carolina
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12 MZ5 13 CX-5
>for the audio file format he is using

Which brings us all the way back around to my first comment on this post: mp3 should have died in the 90's. Like I said earlier, there is not one single legitimate excuse to keep using that lousy file format 2 decades into the 21st Century.
 
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sm1ke

Work In Progress..
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Canada
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'18 CX-9 Signature
>for the audio file format he is using

Which brings us all the way back around to my first comment on this post: mp3 should have died in the 90's. Like I said earlier, there is not one single legitimate excuse to keep using that lousy file format 2 decades into the 21st Century.

We work with what we have. Most people have mp3s or stream audio because it's the most convenient for them. It doesn't make much sense to use FLAC or USB when there is no audible difference in sound quality. The source file is like a car that has a top speed of 150mph, while the audio system is like the 50mph speed limit on the roads that the car travels on.

In Jnclem's experience, with mp3s, there is no significant audio improvement between bluetooth and USB when played through the audio system he has. Does anyone else have any experience with playing mp3s via bluetooth vs USB?
 
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2019 CX-5 Signature
>for the audio file format he is using

Which brings us all the way back around to my first comment on this post: mp3 should have died in the 90's. Like I said earlier, there is not one single legitimate excuse to keep using that lousy file format 2 decades into the 21st Century.
Should have died in the '90's? That's a ridiculous statement, as is your next. The "excuse" to keep using it has to do with acceptance. Every vehicle manufacture supports it, unlike FLAC, which is spotty at best. When we were looking for a new vehicle at the end of 2018, most of the vehicles that supported FLAC, couldn't play high res files, only 16 bit, which is just CD quality. I have over 100 DVD-A's and SACD's transferred to FLAC. Many are 24-bit/192kHz.

Now, there's the issue with processing power. My FLAC music takes up almost 1TB, which is over 1,200 CD's. I couldn't imagine how long it would take for a mainstream factory head-unit to catalog and play them. Some day I'm sure the hardware will catch up, but until then, MP3's will continue to rule the road.
 
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2019 CX-5 Signature
... Does anyone else have any experience with playing mp3s via bluetooth vs USB?
I know you have, or had a Lexus, since you are also on that forum. On my Mark Levinson there is a somewhat noticeable difference between Bluetooth MP3 and USB MP3. Bluetooth is slightly flatter sounding. In the CX-5, I can not tell any difference. I even tried streaming Amazon HD via AA, but no audible difference. As you and I know, the stock Bose system is the limiting factor.
 
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sm1ke

Work In Progress..
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Canada
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'18 CX-9 Signature
I know you have, or had a Lexus, since you are also on that forum. On my Mark Levinson there is a somewhat noticeable difference between Bluetooth MP3 and USB MP3. Bluetooth is slightly flatter sounding. In the CX-5, I can not tell any difference. I even tried streaming Amazon HD via AA, but no audible difference. As you and I know, the stock Bose system is the limiting factor.

I wasn't fortunate enough to have ML in the Lexus I owned. In fact, I had a 2008, and Lexus didn't integrate bluetooth audio streaming until the 2009 models, so I was actually streaming bluetooth via a bluetooth dongle plugged into a 3.5mm aux jack. I could not discern a difference between the bluetooth dongle and the wired 3.5mm aux cord, but that may have been due to the limitations of the aux cord/jack.

When streaming via bluetooth in my CX-9, there is a tiny bit of a delay between pressing the Next Track button and the next track actually playing. I assume USB would shorten this delay considerably.
 
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2019 CX-5 Signature
I’m late to this discussion... I’m using my iPad that is exclusively Apple lossless format (converted from FLAC) and couldn’t be happier with the sound. My system is the stock Bose.

Other than that, I listen to XM radio. I do have Spotify, but that’s for when my wife or kids want to decide on the music. That all sounds like crap anyway :)
 
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