The most common standard you need to look for in Bluetooth speakers or headphones is 2.1 with A2DP. This is the standard that allows for stereo audio to be played wirelessly over Bluetoothany older and you will get mono audio, which is simply incomparable to wired headsets.
There are newer Bluetooth standards like v3 and v4 which have been made to improve upon wireless audio by reducing the need to compress the file being transferred. However, most headphones available in the market wont come with this standard.
You might also hear of a standard called AptX, but you dont need to pay much attention to it any more. This is an older wireless protocol for CD-quality lossless audio, but the majority of phones and headphones dont support it now.
Bluetooth vs Wired: Quality
With the BT 2.1 standard, the audio quality for most music through streaming services and the bulk of your MP3 files isnt noticeably worse than what you get with wired audio. Most MP3 audio files are at 128kbps bitrate, which will be transmitted fine to Bluetooth headphones and speakers, sounding just like it would on your headphones. For majority of users, this is going to be good enough. An easy way to check for the bitrate of your songs is to right-click the file in Windows and go to Properties -> Details. You will find it under the sub-header Audio.
If most of your files are 128kbps, then you are fine to go with Bluetooth audio over wired as the difference is negligible.
However, if your files are at 192kbps, then you will notice better quality on wired headphones over Bluetooth onesprovided the hardware of the headphones is on par, of course.
If you are an audiophile who listens to lossless audio with FLAC files, then forget about Bluetooth altogether. For Bluetooth audio to work seamlessly, it needs to compress your files while transmitting, which defeats the whole purpose of lossless audio.
Bluetooth vs Wired: Convenience
In terms of convenience, Bluetooth is a winner by a huge margin. Since it is wireless, you obviously dont have any tangled cables or a wire accidentally popping out of your phone. And you are free to move around while keeping your phone or speakers in one place. Perhaps most importantly, your Bluetooth headphones arent going to stop working as easily as your wired headphonesthe latter usually malfunction when the copper wire inside the cord is damaged by wear and tear.
On the down side, Bluetooth headphones have to be charged to use, so thats yet another device whose battery you need to keep an eye on and periodically recharge.
So What Should You Buy
Figuring out whether convenience matters more to you or quality is easier if you know what kind of listener you are.
For audiophiles, i.e. people who know they listen to lossless audio and are particular about the audio source of their songs, Bluetooth is a no-go at the moment. None of the Bluetooth headphones and speakers (and we have tried the top-of-the-line stuff from the best brands) matches up to the output of wired headphones.
For people who know they listen to online streaming music or download pirated songs off the Internet, you are most likely getting 128kbps songs. Check out a few of your files with the method mentioned above and if its usually 128kbps, then Bluetooth audio is the better option because of the convenience it offers at the same quality.
For those who listen to 192kbps files and know they have ripped or downloaded music at that bitrate for a reason, you are going to notice a difference between Bluetooth and wired. But the difference isnt enough to make the audio quality a deal-breaker either. The best way forward, in this case, is to load up your phone with your own songs and visit a retail store to try out a few Bluetooth headphones or speakers and their wired counterparts. If you do notice a difference, then you probably want to stick with wired. If the notice is too little to matter to you, then the convenience of Bluetooth makes it a better purchase.