eSynic HiFi Headphone Amplifier Portable Bluetooth Earphone Amplifier Bluetooth 5.0 Receiver 16-300Ω Headphone Amp 3.5mm Supports aptX Low Latency SBC AAC with Gain Switch for MP3/4 Phone Computer

As per title.Can't vouch for battery life as it was barely out of the packaging prior to return. Junk.

Works as described but with a slight issue. The audio quality on bluetooth is excellent. There are two gain settings. High and Low. I bought the unit to work with some old high impedence Beyer Dynamic headphone as I knew they needed some extra power. The unit works well in terms of sound quality. My reservation is that I feel the output could be a tad louder. I found that trying three different headphones, Sony, Bose and the Beyer's I had to run the volume at maximum or very close to it. One device I fed them with fell very short, and that was all running the sources at full volume. That being said, in terms of audio quality. The unit offers great value for money and having a long life rechargeable battery is most certainly really useful. Connection to the bluetooth source(s) was relatively straight forward. As is usual with bluetooth pairing..timing is everything. Worth the price paid and can recommend.