mostly the amp models... the m13 has none...
and the answer as to which one... mostly comes down to whether you like your current amp... or want other flexibility there....
other differences as well... inputs/outputs etc
Thank you! That's exactly what I needed to know. My band bought me an iPB-10 and it's broke down already. Besides you need the iPad to tweak it. I'm using a hot rod deluxe amp that is great but is mono. We have a 3 piece and we center drums and bass. I like the stereo thing because I can get on both sides of them in the P.A. Maybe the HD 500 would be the best solution. I use an X-3 Pod with my DAW so I'm familiar with the set-up.