a 121 will work with a pre that has a fair bit of gain ...
try it ... pointing Null towards the amp at 6 feet will give you an interesting sound ... adds some really nice air ... does not always need to be far to create this ...
sure you can use it ... you can use a can and string if you like
IMHO, adding room to a sound would mean not panning separately because that takes the point out of putting the sound in the room it was in ... you can surely do whatever sounds good for the project you are working on ...
rules in music and sound are meant to be broken sometimes, we move forward by doing that ..
cheers
john