Main features

– plays mp3 files
– support for 32GB USB and 16GB microSD storage
– 3W/4Ω amplifier

The sound and…

– overall sound is not flat, it is probably intended to use with a speaker, low frequencies are dimmed and heights are boosted
– sound using KOSS porta Pro is clear, the underneath noise is very low, heights are very crispy, super fine
– USBs are okay, microSD card slot has push to eject mechanism
– the 3.5mm plug goes okay after few cycles, new has very tight contacts, not soldered well, not straight

Conclusion

++ sound quality
++ USB slot
— click in headphones when plugged in
— does not play wav files