My current amp is starting to screw around with me and my birthday's coming up so im thinking of a new amp. what are your thoughts with the hartke kickback 12? (or 10, 15, etc). because of the aluminum speaker, will it be as loud when it's cold? im just going by common sense... i'll just be using this primarily as a monitor or as a rehearsal amp in my drummer's garage or something. can extra cabs be added? if so, what size would be ideal? a 10"?