Are line-out jacks needed to use an ADC?

Suppose you had a preamp with several pairs of output jacks but no tape monitor, no basic line-out. Could you still use an analogue-to-digital convertor, just running it off one of the standard outputs? I recognize that this would get the volume control into the picture, but would that present an insurmountable problem?
I'm looking at a preamp that doesn't have a tape monitor. However, one of the four set of outputs (two RCAs and two balanced) could be configured as a line-out if that's what I'd want. The only way I'd want this is to maybe run an ADC for transferring vinyl to digital. This is something I've thought of doing, but haven't yet pursued -- and may never get around to trying. Thus, I'm wondering if the pre as is could work.