Dumb file size question.

n80,

As stated above, do not go for lower resolution just because of memory capacity. With a little luck, you can get 4TB for $100 at major stores. Higher resolution files are frequently worth it in the long run.

In case you are looking for a one-box solution, make sure you can attach it to a different DAC. You have already been playing with those things so you are more likely going to do it again at some point than not. It may not matter right now, but Bluesound Vault 2i does not seem to play DSD which is one of the high-resolution formats many people use. Check other brands, too.

n80,

Some time ago, you said that you had no interest in downloads and will go on with CDs. I abstained, forced myself to, from suggesting you consider CDs on a hard drive. You and I have, at this point, downloaded same number of albums (1) and I have no real intention to make it more common. Something will probably trickle over time, I know. I still buy CDs and, unfortunately, records (rarely). I even bought a CD player recently. However, the difference in convenience between CDs and those same CDs on a hard drive is ridiculous. I suggest you, gradually, consider that option. It is really much nicer way of dealing with your music collection. Depending on your car, you may even take the whole collection with you on a trip. It is really better than you might have thought. 

At some point, I read about differences about the source these high-resolution websites get their music from. I forgot the details but there was lots of discrepancy among them, at least at that point in time. Sort of "rip the CD into (let's say) DSD". I have no further knowledge about that, just a faded memory of an article.

For now, and for a quick info about other websites, this has a few mentioned...

https://www.sony.com/electronics/best-music-download-sites-hi-res-audio