theres no rule that says you cant compress the kick and snare together...it will work if you do it...like i said before, usually the compressor settings that you do the track best will be completely different for the kick and snare....if you have plugin compressor, thats no problem...if you have 1 outboard compressor, back to the drawing board...at which point are you compressing, tracking or mixing?....if you are doing it during compression on a digital recorder, id throw it across all the tracks but just use it as a mild limiter to catch the bad peaks....