For USB audio this is a cheap C-Media DAC in a metal case and that is the entire extent of engineering effort that has been considered.
The unit suffers from passing through electrical noise over the USB line direct into the audio signal! When using with an iPad, just loading apps, changing what's on the screen will create noise, and the general cycle can be heard continuously. That electrical noise will be there, its normal, but the audio output side is supposed to be isolated from this noise. This is noise travelling within the device itself! This is not acceptable for what is verging on a professional product.
I got much better results with various audio interfaces (including a £7 USB C aux cable) plugged into a cheap active DI.
The USB socket is much more fussy about cables than other devices, such that it dropped the connection easily on cable that works with other device. It was very happy and stable with an Apple USB cable however as these always appear to have well made connectors.
As others have said it does not request power from a USB-C host yet it is a USB-C device. It only works from ports which always have power which are usually A ports and some badly made USB-C hubs (like one I own). So a standard USB-C cable direct to a mobile device or Mac/PC will not work! The easiest way to make a cable that requests power is a C to A adapter then to use the cable that came with the device.
A neater way is C to USB-B micro (male) at the host end then a micro B (female) to USB-C at this DI box.
The use of USB-C on something that might sit on a stage floor is daft. Sticking with full size USB-B would've made more sense in my view.
Bluetooth only supports the basic SBC codec which is now 22 years old.
Modern receivers should support AAC for Apple devices and AptX or LDAC for other device. This device can not accept these codecs.
All in all the device would be fine where low quality audio will do and being battery powered makes sense when phantom power is not available to power the bluetooth receiver.
For USB audio there is bus power so if all that is needed is to send stereo audio down 2 balanced XLR lines, then this can be done with a separate USB based: Audio Interface/Soundcard/DAC/Headphone Adapter/AUX cable then a stereo DI.
I only need mono for playing soft synths and output everything from my iPAD down one channel, and will not keep this device in my gig bag but instead use a Zoom AMS 22 plus a Behringer DI100 with a short patch cable between. It's a shame as this device would be just one single device but it's not good enough as I'd be feeding noise into the PA before I even press a key on my keyboard.
