I used one of these DEQ2496 EQ's between CD and DAC (AES or TOSLINK SPDIF in/out - all digital) and think that , especially with 12AU7 tubes in the path further down the line, that the EQ would be considered rather transparent. (Some experience in a modern studio environment would be helpful for setup though). This sounded better to me that the software ones I tried (which was years ago), even those within a DAW. I have 2 MiniDSP-HD's and assume those would be easier to use, but I never used the digital to digital version.
You may be able to get one with a trial period.
https://www.sweetwater.com/store/detail/DEQ2496--behringer-ultracurve-pro-deq2496
You may be able to get one with a trial period.
https://www.sweetwater.com/store/detail/DEQ2496--behringer-ultracurve-pro-deq2496