Digital streaming/library

I have purchased a rather substantial 2 channel audio system, and two of the components are a streamer and an audio nas...a melco. I want to build a digital music library. I would love to have the hd level tracks, but the downloads are so expensive. I already have thousands of lps, and thousands of cds. I have iTunes, and it (and rhapsody) allow you to download tracks into your computer...but they are not cd quality. I have a streamer, and I could get the tidal or deezer hi res subscriptions, but do they allow you to download tracks into your computer/nas drive for a digital library?