I don't know why some people try to talk people out of the E10 to get the E17. It is a fantastic amp/dac for the price and just a hair more powerful than the E17. Maybe because it doesn't upsample to 192khz? Newsflash, none of your digital music is over 44.1 unless you downloaded it from a "high res" website. This includes CD's.
In any case if I were you. I would get the Vmoda M80 in white for your gal. If you would manage to find a steal like the one they had a couple days ago on amazon for 130 you would be in business.
E10 for you and spend the extra on her. Then just borrow her M80's when you want to hear a headphone that IMO sound better than your M50 anyway