Art Audio Carissa with Volume Control?

Has anyone used this Amp with volume control?
I only have CD as a source.
What does it sound like?
What do I lose by not having a pre-amp?

I have an Art Symphony II with volume control. The music sounds more natural, loosey, and goosey. When I connect my Sonic Frontiers SFL-2 preamp to the Art amp, I get better defined image and focus. The Art volume control is just a variable resistor added between the source's input and the amp input. You can simulate this with a passive preamp.