You really do not need a high output DAC for it to work with a passive preamp. What is much more important is correct impedance matching of DAC output/preamp/amp combo. Cable selection is also important. You won't be able to use long cables at all.
High output dacs/CD players
I'm interested to know high output dac and/or CD players which can go well with passive preamps. The high output is generally well above the 2V norm of the CD. I know of the Theta Pro gen V dac which is about 6V in unbal RCA and about 7V in bal XLR. Then, there is the Audio Synthesis DAX-2 at 3.6V and also the Altis Ref dac with 4V. Are there more? They all must be highend products. Any CDPs?