I tend to treat my samples/player the same way as a live keyboard on stage (keyboards suffer the same issues - being basically (and rather crudely-sorry) sample players as well)
If your using a lot of loops/sequences and "normal" keyboard sounds, then you may want to get a small on stage mixer or mix internally on your soundcard virtual mixer (most have them now) for each gig - using the mixer as a basic level alligner. (i would also advise a keyboard player to do much the same if he had a Keyboard turret and more than 2 different instruments) - you could then send this mix di to the front of house PA as one would a regular keyboard and have a monitor/keyboard amp on stage to create a focus on stage for the samples.
Placing a sound source on stage helps with balancing stage levels, monitoring and creating a "real world" vibe - which i know guitarists etc etc like....it also helps the audience visualise the soundsource as real, rather than the samples "magically" appearing out of the PA...something i prefer as a viewer.
One could always place a commpressor or eq inbetween the di signal and the front of house desk for balance tweeking in each gig to blend with the rest of the band - sometimes it helps to dirty the sequences as well (even with a tube/distortion pedal) - so you can "match" the crapness one is hearing from the other players. - this helps with balance and fusing in the sampled material
hope this helps a little