Wireless Or Bluetooth Speakers For Budding Musician?

Hi, I am looking at buying a portable dock or speaker system for use with my iPad 4 (music apps such as Korg iElectribe) and various music gadgets such as my Korg Kaossilator Pro and Kaoss Pad 3 and some other synths.

I like performing live and often take all my gadgets round to friend's houses and at a local social club I go to. I have previously connected everything to each other or via a small Behringer mixer and then to a Logitech Mini Boombox but the sound is terrible for what I want (it crackles at high volumes and the bass is dreadful), so I want to upgrade to something better.

I've been looking at the Sony SA-NS510 wireless speaker which seems ideal as it's portable and can run on a rechargeable battery, my only concern is that it is a little on the large side for putting in a backpack. Plus I don't think I'll take advantage of things like Apple Air Play as when I'm using it at other places than my home I won't always have a wi-fi network available. I can connect everything up to the 3.5mm port though and the sound was very good when I heard it in Currys.

Some of the bluetooth speakers seem to be a lot less powerful and for the same price or higher but they have the advantage of being a lot smaller and more carry-able.

Please could someone offer some advice as to what might work well in my set up before I go ahead and buy the Sony.

Thanks very much.