Power supply cable was broken, I had to replace it with new one. Seller offered me a discount for next purchase. I do not plan to make second order here, but in generall seller is communicative and reliable. Product slightly increases output sound. Thanks!
The product is does indeed convert digital signal to analog but it does also nasty 'pop' sound artifacts when input stop sending signal (TV in standby, changing channels, changing sample rate etc.). I tried to open dispute and they didn't want to acknowledge they have an issue! So I ended up having broken product at home.