As for the original question, I've owned both and the Dynahi is superior in every way to my ears. This is not just with the K340... also with K240S, K271S, Grados, etc.
That said, if you've only got low impedance headphones the Dynalo is a great value. It might do well with the easier to drive high impedance headphones like the HD600[and family], but it doesn't cut it for the K340s.