Suggestions for preamp compatible with Pass X250?

What are you presently using?

Presently using an old Crimson Electric 510 with a Musical fidelity X-LPS v3 (Denon 103 on SOTA Star setup). Was also using an Anthem TLP-1 which was way too low on gain (planned to sell anyway). The 510 was 'borrowed' for the time being from a second system where it is matched with the 520 amp.

I would suggest staying within the Pass family. If the X-1 is too expensive, and it doesn't have phono, then you could find a used Aleph P and Aleph Ono for about $2400 together. I used this combo with Pass monos before upgrading to the X-1 and XONO which are slightly more transparent and quiet for about $4000 used. I loved the black one-box, simple ergonomics of the Aleph line. Another advantage is that you can go balanced with either the Aleph or X lines for lower noise and 6db more gain.