Expensive, yet noise

I have purchased the product in hopes be somewhat higher price would be accompanied with better quality. Unfortunately, the hope has not been fulfilled, because it is to hear a faint chirping in silence. I guess that comes with the included AC adapter, but that should be tailored to the product. So the item returned. I then the CSL at random - Audio bought digital to analog converter, which costs about half that - and what can I say: it has no problems with such noise and work despite the lack of sync LED (looks anyway no one in the company) 100 % satisfactory!