Re: GK 250ML
I had one back in the 80's. It reminded me sonically very much of the Tom Scoltz Rockman with a pair of 50-watt power amps and speakers.
I fitted mine with a switch to disable the internal speakers when i was using larger extension cabs, and a drum fitting on the back so i could clip it onto a stand. I used it at many gigs with a 1 x 12" extension cabinet on each channel. It definitely is 'the sound of the 80s' in a box' (just like the Rockman, although the latter is only an exotic headphone amp). It does those sounds superbly, although it had one sound I couldn't get ... the simple fat warm clean sound of a valve amp.
At the time, my main guitar was a Washburn Bantam, an all-wood Steinberger clone, so with that guitar and the GK 250ML i was able to get to rehearsals around Sydney easily via buses and trains. Having the overdrive and delay built in was another bonus, didn't need to carry a mass of pedals and cables on public transport.
Eventually i sold it to get back to the more traditional valve amp sound, but it was a great little amp that did a lot at very high quality, and it was ideal in it's time for those 80s sounds .... almost surgical cleans, compressed, slight chorus and delay, and very useable overdrive (in context).
I think I have some recordings of a live gig and also studio demos where i used this amp. Of course the recordings are on cassette, I'll have to digitise them so I can post them.