Volume matched inputs on a preamp?

I'm not quite sure how to ask this - but I'm wondering if there are any preamps that allow you to set the volume by the input so you can volume-match one input to the others.  So many DACs have different output levels, it's hard to compare them.  If you could set the gain by each input to volume match all the inputs - that would be a lot of fun.  Yes, I send digital signals from a single source to different DACs and like to switch between them to see how they may differ.  Tube or solid state doesn't matter, but I'm guessing it'd be easier with a solid state preamp.

Multiple google searches for key words did not turn anything up.  

Thanks!