analogue synths

you can get cheap-ish 80s/early 90s 1U rack synths on Ebay and then connect them via MIDI to a box with knobs on to get the benefits of the interface. i forget who make these control panels but can find out for you.

also if you're handy with a soldering iron PAIA have an analogue synth kit which has plenty of knobs

My personal fave is the (Sequential Circuits) Pro One - twin independent oscillators / sequencer. You can do almost anything on it - for the record, apart from the drum machine, it was the only instrument used on Yazoo's Only You. It's a mono, but what the heck...I've never heard a polyphonic used to any great effect!

didn't basic channel (and vainqueur, wherever he went) use the sequential circuits equipment?