If you want good headphones, the hd600/650 is an excellent choice. They are very good. Once you have them, listen to Spotify if you already have it. If you're not happy, at that point it won't really cost you anything extra to move to a higher quality streaming service like Tidal, Qobuz, I've been using Deezer for about 2 yrs and have been very happy with the quality and interface of it. But getting the headphones is the first step and then work on the source if you think you can get a better result.