Searching for CD/DVD Player with volume control

I have an Oppo 970HD DVD player that I run directly into a power amp, using the Oppo's volume control to operate the loudness level. This bare bones 2 channel system is for music and movies alike.

I'm looking to step up to a better DVD/CD player for improved CD playback while keeping the bare bones set up. My budget is up to $400 on the used market.

What are my upgrade choices for a DVD player with variable output?
Marantz, Cambridge, Arcam, Pioneer, Denon, etc?