The OPPO HA-2 will perform as a DAC for your iPod/iPhone and your PC. The Sony I don't know but probably. The OPPO is 400€ here in France, so better to try it before.
Some DAP can be used like a DAC for your PC too.
Ok, so after a week with my W50 and iPhone 6, I decided to exchange it for another W50 from the dealer. I told them it is faulty on the right side connector. The cable came off the earphone atleast 4-5 times in a week with normal usage.
They said the new W50 will ship in a few days as they are out of stock (ETA is Nov 2).
I am very happy with W50' sound. It certainly has more bass compared to W30, but its smooth and not hard bass. I was able to hear separations of various instruments clearly. I don't know about sound stage and all that as I am an amateur and only listen on my iPhone/iPod. But, overall this is a great earphone. Only thing is, at a price point of $549 or $599 (regular price on the street), we do have several good options I guess (IE800, Grado GR10e, SE535 etc.,).