Are you currently using the Aurender as just a DAC, and is the preamp just a volume control on the DAC? Either way with the reputation of Aurender using the preamp section probably won't degrade your sound.

What I would do is experiment. I'd start with the Zen amps volume set about 3/4 full and the Aurender at about 3/4 full and then just play around between the two volume controls to get to your listening levels and you should notice some subtle differences in the character of the sound and have a preference. Get the two volume controls set up at about your normal listening level and then you can adjust the volume up or down with the remote as needed.

I bet it sounds good and having a remote is a good thing.

I would second Lon’s post. I have seen, and tried a common technique of
1. Setting Pre-Amp volume to 12 o’clock intially.
2. Turning Power-Amps up to your normal listening(not your rock out level)
3. Leaving Power-Amps at that Volume, and using Pre-Amp Volume to control the level from there.

In the end try it all till you like what you hear, and/or use it to adjust the sound of your system like an eq. It will be very subtle on most equipment I assume. I know that I have heard a differance, usually in the weight of the music. I haven’t used my Monoblocks in awhile, but I would assume it is the same. Stepped Controls making it easier(unless you crank the Poweramp volume, which is also viable unless the manufactuer says otherwise.)