[portaear]

I've been on a bluetooth kick recently, trying to free myself from cables and using bluetooth headsets at the gym and in the car.  The earphones I had been using were the highly touted Panasonic RP-TCM125-A , picked as one of the top wired earphones by wirecutter. These sound crisp, full, and lively, for only $13 - $14.  
 
All of these earphones were tried with iPhone 6s Plus, which still has the headphone jack.
 
I first purchased the Plantronics BackBeat Fit ($75 at CostCo), which despite an open design (does not seal the ear completely), sounds pretty darn good, relatively speaking.
 
Then I purchased the LG Tone Infinim hbs-910 ($49 marked down from $79 at CostCo), which sounded like the worst pair of earphones I have tried in a long time. The sound was tinny, flat, and completely lacking any bass. I was shocked at how bad these sounded, compared to any earphone I had tried in a while.
 
Then I purchased the Apple Powerbeats 3 ($149 from CostCo), which is 10 times the cost of the cheap Panasonic RP-TCM125-A earphones.  I eagerly opened these up, and tried on the various earbuds.  First impressions, not too bad.  I could hear a decent range, from decent bass to decent treble.  After a couple of songs, I turned these off, and plugged in the cheap RP-TCM125-A to compare.  To my shock, the RP-TCM125-A sounded much crisper, fuller, and deeper.  It was no comparison.  
 
I'm shocked that even "premium" bluetooth earphones like the Powerbeats 3, which retail for $200, purchased for 10 times the cost of the cheap RP-TCM125-A , cannot compare to the cheap wired earphone.  It seems even with the latest W1 chip, and all of the latest bluetooth tech, bluetooth earphones just can't compare to wired earphones.
 
I'm honestly not convinced that bluetooth earphones are worth the premium or the hassle, compared to wired earphones, which sounds vastly better and are 1/10th the cost of these premium earphones.
 
It was courageous for Apple to remove the headphone jack on the iPhone 7, but I'm not convinced it's the right move.  If bluetooth can't even match wired headphones for basic sound fidelity, why bother?
 
This recent series of bluetooth venture has me somewhat disappointed at the current state of bluetooth tech.  It seems no matter how much manufacturers want to deprecate the wired earphones, they aren't close yet, not in quality, and certainly not in price.

 

[Niouke]

If bluetooth can't even match wired headphones for basic sound fidelity, why bother?
 

Most people don't have the reference points to actually detect that the music sounds worst on bluetooth over wired. When they plug their Bose QC35 in bluetooth and listen to their 128kbps mp3 or youtube rip, for most of them it is actually the best sound quality they have ever heard, so why bother looking any further? You don't need something you don't know about.
 
Hell a few years ago it took me a while to actually detect why my music was lacking detail and stereo separation when I switched to a bluetooth module over the regular smartphone output. I've also asked people to try their Parrot headphones in wired mode for once, they couldn't detect a difference.

 

[Niouke]

as of the "why" there are more knowledgeable people that can answer precisely, however I can say that the bandwith of bluetooth doesn't permit to send enough data per second to reproduce a sound as good as an analogic cable would.

 

[castleofargh]

a BT headphone is a DAC+amp+headphone+wireless transmission system+enough battery for all of the above. it must be light enough and small enough for a user to enjoy using it. and at a price people will consider paying. so of course there will be some financial and physical limitations the designer cannot forget when making the headphone. the target user is a guy who doesn't want to be bothered by a simple cable, chances are that guy also won't appreciate being bothered by anything else. so sound quality becomes a secondary concern way below all the other concerns in most cases. 
 
putting a wired headphone and a BT headphone side by side isn't fair game IMO. but I agree, most BT headphones have a sound that sucks, objectively or subjectively. for starters, all those I got to try so far had some audible background hiss, probably due to a bad amp section. itself probably due to how tiny the battery is.
some technological innovation might be needed to really get a long lasting well performing BT device that's light. but even then, I personally enjoy using a BT headphone quite a lot. not for critical listening or anything, but the same way I will turn on the horrible radio in the bathroom. it's just nice without any pretense of hifi.

 

[LajostheHun]

The BT hiss is certainly there, but it usually masked by the music easily.
BT these days can actually sound very good, I bought some BT APtx dongle that basically convert any headphone into a BT headphone so I can directly compare it to it's wired self. Yes the comparison is not ideal since I have to unplug/ replug , so there is time lost and the human auditory memory is rather short indeed. Having said that the difference I perceive is really not that much really. Aptx compresses CD/Flac similar to the 320kbps MP3. I use 16/44.1 FLAC files played from my phone. The new Samsung S8 has the new BT 5 version which gives significantly larger bandwidth and will easily accommodate the now emerging Aptx HD codec with it's 24/48 lossless streaming ability. Snobs will always find a reason to tether themselves to their Head Fi gear, I on the other hand will embrace emerging techs that free me yet still lets me enjoy my music the same way.
Yup this is the dongle I'm using right now. Costs $26 shipped on Amazon