@OP you can look at the audio engine d1 for the dac, if someone can get it from the US, even better. But remember that USB powered dacs can't really push out full line voltage. And are also not very good to drive hard to drive headphones, m50 should be fine though (38ohms acc to the interwebs). But still for the money, it is a really good dac, best part is, you can pair it up with a poweramp as the volume control on the dac allows it to be used as a pre-amp (somewhat, don't kill me for this veterans, I know it's not a pre amp
). But, still it's a really good dac, specially if you choose to go the active speakers way. Reason being, you can put the dac on your desk and max out the windows and the dac volume, then set your speaker's volume to the max you would ever want to be. And you have fixed one of the most irritating thing about active monitors (most of them have the volume at the back, plus when you have two, you have to adjust both), this way you can control it from the desk with the dac. Just my two cents (paise)
. Hope this helps, I am a no pro though, only a semi noob
.
*question to op, does your laptop/computer have s/pdif out?