For a transport/streamer I’d recommend an Innuos Zen Mini Mk3 with external power supply because it does four things that could be of benefit to you. It’s a very good streamer, has a built-in CD drive with internal storage, a transport, and a DAC all in one. So in theory (read on) it can do everything you’re looking for in one box and can be had new for $2000 with the external power supply that significantly improves performance so not really optional IMHO (although you could add it later). With its CD drive and internal storage the Zen Mini makes it child’s play to rip all your CDs and have access to all of your music at your fingertips via the Innuos app. How nice would that be versus messing with a traditional CD transport with no ability to search, shuffle, or create your own playlists, not to mention having to get up to pick out and change CDs? But not only that, you’ll now also be able to stream from an online subscription service (I recommend Qobuz hi-res subscription for $15/mo. that I’m thrilled with) and have an almost unlimited selection of high-quality, new music also at your fingertips. As a recent streaming convert I’m finding so much awesome new (to me) music on Qobuz I can’t find time to play it all — a high quality problem that has me enjoying music more than I have in years, and I barely play my own CDs anymore.
So now you’ve got all your music along with a world of streamed music literally at your fingertips, and at this point you could then just hook the Zen’s analog output (using its internal DAC) to your preamp and be completely done. Couldn’t really be simpler. But at your budget I’d upgrade to a better DAC, if not immediately definitely down the road a little. Given your sound preferences and budget I’d recommend a used Bel Canto DAC3.7 with VBL power supply as it provides tons of refined upper-end detail but still with plenty of natural tonality, excellent bass, and a deep, holographic soundstage. There’s one available on US Audio Mart now for $2500, which is a good price given it retailed for $6000 and incorporates technology from their upscale Black line. If it doesn’t work for you, you could likely sell it at little/no loss so a very low-risk option.
Another good DAC option would be a Schiit Yggdrasil, which is an R2R DAC that I’ve not heard personally but from what I’ve read seems to mesh well with what you’re looking for and can be had new for $2500. And I believe Schiit May offer a trial period so it’s also a low-risk option.
Just a few other options for you to research/ponder, and best of luck in your search.