I have a D1 and love the simplicity and sound quality of it. I especially like MQA files, but I know that's somewhat controversial. To my ears, they sound considerably better.
I would recommend you also get Roon. The Lumins are Roon compatible and it would make things very easy for you and your girlfriend to catalog, find and play the music you love. I've had Roon for 3 years and do not have any desire to try alternatives. It's powerful, intuitive and sounds great.