There is controversy in this industrial as to whether a digital volume is just as good as analog volume control. At 32 bits, most engineers say it doesn't matter. I have always been of the opinion that digital volume can be compromise, especially at low listening levels.
That being said, adding an analog volume control to your output could affect the output impedance driving the amplifier. You are, essentially, placing a "passive preamp" between the DAC and the amp.
That being said, adding an analog volume control to your output could affect the output impedance driving the amplifier. You are, essentially, placing a "passive preamp" between the DAC and the amp.