If I could recall it right the ms-50g has only two hi-gain amp sims available (Diezel Herbert and Engl Invader). The high gain amp sims are ok but not great. You'll get a lot of fizz (hi frequency noise) pass 2 o'clock on the gain knob. Hence, suggest to keep your gain conservative.
I see, yun lang pala available sa MS-50G, pero nung naacquire ko yung G5 ko, the first thing I did is to check and compare all the high gain amps, and my top 2 fave is the ENGL Invader, the 3rd is the Diezel Herbert.
I use the Combo/Stack Power Amp(less harsh/fizzy than Direct IMO) kahit in front of an amp,
the Combo/Stack Front's tone sucks for me even though it is the must supposed to do
@metalheadz, try mo na rin sa preference mo, kasi may some point na natural sounding yung included cabinet sims nila, minsan fake sounding din just like the older zoom.