Which headphone amp would you recommend for use with both the k701 and DT 990? Preferably I would like something with two switchable inputs, and around the ~$250 / £150 mark. At the moment the matrix m-stage seems to be top of my list (maybe with the op-amp biasing mod) I would also consider...

The day finally came when my old speedlink medusa home edition headset died, and I think it is time to treat myself to a decent replacement. I remember at the time they were described as being impressive for the price range (£50), but I assume things have moved on since then!   Coming from a...