Need suggestions for a $1500 used system for my daughter.......

I still say the Google Chromecast Audio puck is simplest cheapest way to stream up to 24/96.
It finds your home network and basically sets itself up, hardest task is giving it a name... Lol.
I use two of them in my house for older analog only systems.
SQ is excellent IMHO.
It only has a 3.5mm out but that can do both analog with a 3.5mmto twin RCA cable or a mini toslink adapter for a digital output.
I tried both on my Peachtree and actually preferred the analog output.

Only downside is no longer made but still some nos units on eBay at $50 to $55 Max.
Gets my vote as easiest streaming I have ever dealt with.

How about one of the Peachtree integrated that has a tube in the signal path only.
I had one for my second system and was very impressed and it had inputs to cover just about everything!
Plenty on the used market around $500 or even less.
Even looks sort of art deco Chic!
Plenty of money left over for a cheap streamer like a Chromecast Audio or similar.