A pre-amp will always be best for volume control. A good pre-amp will open up the soundstage and do all sorts of wonderful things IF you have a good source and DAC. If you don't, a pre-amp will show up all the warts in your front end and make your system sound terrible, just the same as if you put revealing speakers in a lesser system.
I'd think of a digital or similar volume control as a stop gap to get your system up and running while you look for a symbiotic pre-amp, it must match.