When comparing AKG K391 NC vs 66 Audio BTS Pro, the Slant community recommends 66 Audio BTS Pro for most people. In the question“What are the best headphones?” 66 Audio BTS Pro is ranked 21st while AKG K391 NC is ranked 61st. The most important reason people chose 66 Audio BTS Pro is:
The BTS Pro is quite robust and can withstand some minor splashes of sweat or rain as these are sweat-proof. They are not completely water-proof though, so you should not get them soaking wet.
Specs
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Pros
Pro Good accessory bundle
The accessories included are all very useful. You get two 3.5mm headphone cables, a USB charging cable, silicone ear tips, a travel pouch and an airplane adapter.
Pro The headphone cable can be detached from the control module
You can easily replace the 3.5mm cable should it get damaged. You can detach the 3.5mm cable from the control module which is very convenient. Other noise cancelling modules have fixed cables, so you’ll have to replace the headphones should the cable get damaged.
Pro Integrated microphone
You can take calls with these headphones on. A microphone is integrated into the remote which makes answering calls fast and convenient.
Pro Decent active noise cancelling
A good amount of noise will be blocked from mixing in with your music. Loud, low-pitched sounds may still be clearly heard though
Pro Compact noise cancelling module
You aren’t likely to have issues using these on the go. Most active noise cancelling in-ear headphones have large control modules, while the K391NC has a fairly compact and light module. You can easily use these headphones while walking and comfortably enjoy active noise cancelling with your music.
Pro Fairly detailed and rich sound
The highs are quite detailed, yet do not get harsh. The mids are slightly forward, so vocals and instruments can easily be heard. The bass is not very powerful but is tight, so you’ll get decent punch from your music.
Pro Great for use when outdoors, going for a run or working out
The BTS Pro is quite robust and can withstand some minor splashes of sweat or rain as these are sweat-proof. They are not completely water-proof though, so you should not get them soaking wet.
Pro Good sound quality with focus on the lower frequencies
There is good detail in the highs and the mids can also be heard clearly with very little muddiness. The lower frequencies are boosted, resulting in a good level of depth and power to each bass thump.
Pro Will stay snug on your head
The BTS Pro ear cups sit on the ears with hooks keeping them in place. The flexible connecting band provides good clamping force and can adjust to your head size with continued use. Combined with cushioning on the cups, these are comfortable to wear and will stay in place.
Pro No long cables to deal with
Bluetooth connectivity allows the BTS Pro to connect with smartphones and compatible music players wirelessly, so cables won't be an issue.
Pro Companion iOS app adds extra functionality
66 Audio's Motion Control iOS App gives users added functionality, including EQ control and presets selection, battery status indicator, and even headphone position tracking. These features can improve the listening experience and also minimize the chances of you losing these headphones.
Pro Can last through multiple long listening sessions
With up to 40 hours of playback time at full charge, it's more than enough for most listening sessions. You won't have to charge these frequently.
Pro Hardshell case makes transport more secure and convenient
A hard shell carrying case is included, which can protect the headphones from minor impact and also make transport much easier. The case also has good aesthetics.
Pro Can be folded to a more compact size
They are easy to bring on the go as the ear cups can be folded into the headband. This further reduces the already slim and compact size, making them easy to chuck into a bag when on the go.
Pro Ear cup functions as a remote
The right ear cup of the BTS Pro features buttons for controlling headphone features. You can play/pause tracks, increase/decrease volume as well as answer/end calls by pressing the corresponding buttons, negating the need to pull out your phone to do so.
Pro Allows taking calls
You do not need to take the BTS Pro off in order to answer incoming calls. There is a built-in microphone which allows you to easily take or make calls in the middle of your run or workout.
Cons
Con Limited inline controls
The inline remote only allows you to play, pause, and skip tracks. You can’t control volume levels though.
Con Some distortion can be heard at lower volumes
There may be audible levels of a scratching sound or distortion when using these at lower volume levels. This can be quite distracting, and can have a negative impact on your listening experience.
Con Motion Control App is for iOS only
At the moment, users of non-iOS devices will not be able to take advantage of the companion app's functionality. However, 66 Audio have announced that an Android app is currently in development.