Noodles speaks the truth, not to mention Devin Townsend using the 5150, and not
the II as well. To my ears the +/II sound more fizzy and compressed, just less articulate in general to the original.
I really want to try a 5150/6505, ive only ever heard one once in person, and it sounded terrible... but everyone on here (almost) reckons they are fucking killer, so im thinking there must have been something wrong with the one i tried... it was really nasally, 'hissy', and generally not very nice to listen to..
They do, they're a full frequency amp... many complain that they get buried by other amps in a practice/rehearsal too... HOWEVER
, mic them up (me thinks a closed back Mesa 4x12 loaded with V30's is the best match) and listen to the amp IN THE MIX
. IMHO, an amp needs to sound great when listening to the mix, not standing in front of it.
Interestingly, Mick Thompson (Slipknot) was addressing this when designing his sig. Rivera head/cab, and REALLY
focused on what it sounded like in a large-ish room, mic'd up, and in the company of bass and drums... and not what it sounded like standing in front of it. Mentioned something to the effect of "It's much easier to take out frequencies in the mix that you don't want there, then to try to put them in".