Pass Labs XA25 without preamp (from a variable output source) vs INT25

Hi!

I just have a single source system (a DAC with a high quality variable output) so what would be the best aounding option? DAC direct to XA25 through the variable output or DAC with fixed output and an INT25?

Reading between lines it seems INT25 looses some transparency and gravitates to a warm sound compared to the very clean and transparent sound the XA25 provides. I love a transparent, rich and 3D sound but I don't want a lean sound. 

Anyone here uses the XA25 without preamp from a high quality variable output source?

Thanks!