The Magni is a good amp, just not a great pairing with the HE400i, the Aune T1 is also good amp also, just does not have the current the HE400i likes but is quite good with HD650 and K7XX. Best combo DAC/amp that is reasonably priced is a Teac UD-301. It pairs very well with the HE400i to me and you can use the DAC output at the same time you are using the amp. The thing to remember is you also need to consider how loud you want to listen at, for me its a very safe 68-75dB with peaks in the lower 80's dB. If you are listening at much higher volumes then the choice amp becomes more important. I would suggest saving until you can get to the $500 range for DAC and amp since I feel this is the sweet spot in price to performance, at this price you can get a Modi MB and Project Polairs, a really go pair that can drive almost everything. Or you can go one piece at a time and DACs and amps in the $500 range are quite good.