Denon Receiver as Pre-Amp with Linkwitz Orion?

I am trying to set up my two-channel system using a Sony SACD Player --> Denon AVR1910 --> Linkwitz Crossover --> ATI 6012 amp. Everything seems to be set up properly, with RCA cables out of the audio inputs in the Sony into the "CD In" in the Denon, then out of the audio outs in the Denon into the inputs of the crossover. Unfortunately, I cannot adjust the volume with the Denon, so everything plays incredibly loud (there is obviously no volume control anywhere else in the chain).

Is there anything I can do? Am I doing something wrong, or is it possible that the Denon is defective?
Wrong outputs. The ones you are using are not going through volume controls. See if in the menu you can change that. OR, if you have some other pre outs.
It may or may not havee a volume controlled pre out.
The one you ARE using is like for a tape deck or other no vol controlled output.
I took a quick look at the specs. for the Denon AVR-1910 and I did not see any analog pre-outs for L&R (or center and surround) speakers. The only analog outs I see are RECORD/TAPE which will not work because they bypass the volume control, and a zone 2 output which may or may not bypass the volume control.

You can try the zone 2 output to see if it works, but that may bypass some of the other features you want from the HT receiver.

I think you may need to consider a different HT receiver or a simple 2-channel pre-amp if you don't need HT functionality.