Check out Peavey Escort. It has five channels, built-in mixer, stands, effects, even a mic and cord. It is all self-contained and has rollers.
It would seem to be perfect for what you want. It has really good, clean sound, and even has a set of RCA in-outs.
The logitechs are good-sounding powered speakers, but you would need a mixer with them.
DonM