You can do this, but I have a warning and suggestion....
Warning: Having a "hard" volume control is handy to make sure you don't overload the amp. Also keep on mind that while iTunes has a volume control, the rest of the OS and apps have separate (or no) volume adjustment. This can be dangerous.
Suggestion: An external DAC improves the sound. Some DACs have volume controls. Remember that the DAC's quality has more to do with the "analog" stage of the design. I see people worry and argue about the "digital" processing a lot, and totally forget that most of the DACs character comes from the analog section.
Warning: Having a "hard" volume control is handy to make sure you don't overload the amp. Also keep on mind that while iTunes has a volume control, the rest of the OS and apps have separate (or no) volume adjustment. This can be dangerous.
Suggestion: An external DAC improves the sound. Some DACs have volume controls. Remember that the DAC's quality has more to do with the "analog" stage of the design. I see people worry and argue about the "digital" processing a lot, and totally forget that most of the DACs character comes from the analog section.