Hi bemuzic thanks for quick reply, it is the reverb in this Clip, dont know if the Amp is yellow or green lol, but you looked quite surprised at how it sounded with the reverb, so is this Reverb the "Boss RV-5" i love that Tone, sends shivers down my neck.
Well, with the usual stipulation that I am not an electrician or electronics engineer and that if you try you do it entirely at your own risk, no. Seriously the only significant difference is that disposable batteries are 1.5 volts and rechargeables are 1.2 volts. Either they will work as normal (as with the Micro Cube) or not, in which case you just have to put the disposable batteries back in. I would certainly try it.
I only have the digital manual (as I got the amp second hand on eBay) and it doesn't say not to use rechargeables in that. I have had it for 9 or 10 months and I don't think I have used anything else. Seems to run almost forever of them. There is no drop in volume compared to using the mains adaptor. They have a slightly lower voltage but the worst that could happen is that it wouldn't work (which it clearly does).