Yes, that can work. I output my Lavry DA-10 directly to my tube amp. Got rid of the preamp several years ago.
I use a Squeezebox player with the digital out to the DAC. I control the listening volume with the Squeezebox's digital volume control.
One point of caution. This works best if your DAC has a variable volume out of its own. (The Lavry does.) Set the DAC's output so that your loudest source is at your maximum desired volume in the listening room. This does two things. First it allows you to keep your source's digital volume in the top half of its range so that no resolution is lost. Second, in case the digital volume control software burps and accidentally goes to max volume, you'll be loud but won't accidentally overdrive a speaker.
If you're using the DAC's or the power amp's volume control as your main system volume knob, these two items are not an issue.
If your DAC has a fixed output volume and your power amp has a fixed input sensitivity, proceed cautiously, especially if the source, when turned up loud, is capable of overdriving the speakers.
