It's going to depend on the particular pieces in question, but many around here will say they prefer using a pre or integrated to using the volume control in their DAC. I have the Perfect Wave DAC, and even inserting a very inexpensive Pre (an old Adcom) was an improvement over the PWs volume control (which sheds bits under 50%; bad for a quiet listener like me). I ended up with an integrated (Pass INT-30A), and am very happy; I'd seriously consider the integrated route, esp. for a second system.
John
John