I ordered a pair of Sennheiser HD650s and I am wondering if it's best to get a Topping NX4 or Dacport HD to drive them. Portability is a factor (maybe the Topping isn't great for commuting), but because I will not have my Denon receiver for a year (I am not sure even if it was suitable for these headphones) I was thinking of maybe getting the Dacport HD and then something more powerful for home. I am afraid that the Topping would be more than enough so that I will not get anything better! How much more powerful and verstaile is the topping than the Dacport? Any other suggestions are welcome!