The best in terms of price is the Chromecast Audio. It also has an internal DAC so you could go from that direct to the amp. Or you can connect it to your dac. And it is tiny and can just dangle out the back of the amp or dac. It costs only a few tens of $ new on eBay (they don’t make them any more). The sound quality is excellent for everything, especially for Spotify and CD quality files. Spotify Connect recognises the device and so streaming from your daughter’s phone is so easy.
The device, made in the millions hence the low price, was the best value piece of audio equipment ever produced.