Avantree Audikast Plus bluetooth audio transmitter

I recently purchased a Avantree Audikast Plus Wireless Audio Transmitter for around 50 GBP from Ali Express. This device offers AptX Low Latency support and can accept a 3.5mm stereo input (as well as optical and USB audio). So you can use it with practically any device that outputs audio to convert it into bluetooth audio.

My main thought was that with AptX LL support, it might be useable plugged into the headphone socket in a mixer to allow the use of wireless headphones. Now, I'm not a DJ, so I can't really report on whether it is 'usable' for this. Latency seemed low to me, but I couldn't really tell any difference between my headphones (Plantronics Backbeat Pro 2) connected to the Audikast with AptX LL vs the headphones connected to the laptop at the mercy of whatever bluetooth codec windows uses, which I think is SBC.

I thought the Audikast might also work over a longer range than my laptop bluetooth, but actually there was no difference. If there was any difference, it was actually in favour of the laptop's built-in bluetooth. It is considerably better than the 'Bluetooth 5.0' usb dongle I have in my PC though.

Using USB audio, I had a similar problem to the Cyboris X3-PRO-N bluetooth speaker in that the first 250ms or so of sound is cut off. Once an audio signal is going, then it's fine, it's just going from silence to sound you get the problem. When no audio is being output, the input selection light on the Audikast flashes on 'Opt' (optical). Once sound starts playing over USB it will then switch to USB, and stay there until about 15s of silence have passed. At which point it goes back to flashing opt.

Unfortunately there is no way to manually choose the input source. I'm sure they could have included this, e.g. press + and - buttons for 5s, use + and - to select the input you want, with no input selected being auto, then after 5s it sticks on that setting.

Unlike the Cyboris speaker though, when you open Ableton, it switches to USB audio automatically. So no problem with sound being cut in ableton.

With avantree mic selected as audio input in ableton, audio quality for sound was terrible. After turning that off, sound quality was good and no noticable latency.

The Audikast Plus supports 2 sets of headphones connected at once, which could be useful for 2 people wanting to watch TV with headphones. But I don't think I'd ever need this.