Good transport for under 1K?

Take a look at Cambridge Audio's CXU HD.  It is a universal (Redbook, SACD, Blu-Ray, DVD, etc., etc.) transport that also streams.  Mine is paired with a Chord DAC and sounds as good as any other transport that I have had (40 years from vinyl to streaming) or heard.  Love it!  Priced +/- $700.00.

I have a rotel rc 1590 preamp with built in DAC. So, I could use the Cambridge audio as a transport?  How would I connect the two for the best sound?

This is an excellent transport that I have hooked up to my DS Sr. via I2S. Also as it is a half size component takes up very little shelf room.

https://www.audioadvisor.com/prodinfo.asp?number=NPCDT8

Woo Audio has been in business for many years and has a reputation for building quality products.
No affiliation, I know some satisfied owners of their amps.

http://www.enjoythemusic.com/magazine/equipment/0114/woo_audio_wtp_1_wds_1.htm

Maritime 51,

If your Rotel has an RCA  digital input for the DAC section it should be no more than running a good 75 ohm digital rca cable between the Cambridge and the preamp, but check your owners manual.