66 Audio BTS Pro vs Jaybird X3

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.

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.

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.

Bluetooth connectivity allows the BTS Pro to connect with smartphones and compatible music players wirelessly, so cables won't be an issue.

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.

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.

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.

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.

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.

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.

Exposure to splashes of rain or sweat won't easily damage these earphones.

The highs are crisp, airy and forward so detail presentation is very good. Bass is fast and controlled instead of boomy, so it does not muddy up the overall sound. The mids sound natural and do not get lost in the mix.
This sound signature works well with a wide range of genres and rock, pop, hip-hop and EDM will definitely sound great with these headphones.

The X3 comes with wing tips that you can attach to the earpieces. The tips enhance the grip of the headphones in the ear, and will help keep them secure even while you are running

The in-line remote will allow you to control music playback, adjust volume as well as answer/end calls.

Integrated into the remote is a microphone, so you do not need to pull out your phone should a call come in. Mic quality is pretty decent, and your voice should be easy to understand on the other line.

You get standard silicone ear tips in different sizes, along with a carrying case, different sized wing tips, premium Comply foam ear tips in different sizes, cable management clips as well as the charging cradle with micro-USB cable.

The older X2 model had bigger and heavier earpieces which made them prone to falling off, and also made it difficult to use the earphones with a helmet or a hat. The X3’s earpieces have been redesigned to be smaller, while the internal batteries have been moved from the earpiece to the remote. This helps keep the X3 in-place inside the ears and at the same time makes these earphones easier to fit under a hat or helmet.

The X3 gets around 8 hours of playback time from a full charge. This battery life is much more consistent compared to the previous model which had spotty battery life.

Signal quality is pretty stable with minimal distortion or drops, even if you are on the move.