The Poly 800 is a battery powered, portable, 64 memory, twin oscillator, programmable polysynth with incrementing controls on push buttons, a built-in step time sequencer and MIDI.

Geoff Downes is a Fairlight equipped, multi fingered keyboard player with Asia.

They met and fell in love. This is the story of their affair, as uncovered by Colbert over a dodgy phone line.

How did you get your Poly 800?: "When we did an MTV satellite broadcast in Japan, quite a lot of people from all the companies came round. The Korg people said 'have you seen this?' I tried it in the dressing room and put it into my keyboard rack straight away. It seemed a lot more versatile than the Poly 61, and it's easy to operate. It looks as if it might be confusing, but in fact it's very simple once you've learned the basics.

"You don't have to type in a number, you can feel your way through, so if you want to shape the filter, then providing you've selected the right parameter, you can keep your finger on the button and it will slide up or down the values, just like urning a knob. You can always 'hear' what's going on.

"I've also got a PPG, and there you have to type in a number, hear the result, type in another number, listen to that, and try to estimate what you want."

Have you programmed many of your own sounds into it?: "Yeah, quite a few. I did a whole load of sounds and then was stupid enough to leave it on all night. The batteries died and wiped the memory. But that is a great facility, the batteries make it totally mobile, I don't think there's another polyphonic instrument like that. But it would have made more sense to have one cell for the memory and separate batteries for the rest."

Is it actually that easy to carry around?: "I tried it on stage one night with a Nady radio mike and it is amazing. I took a walk to the back of the auditorium. It weighs about the same as a guitar but it doesn't balance as well. It needs something like a small neck with controls on it."

Any problems?: "It's difficult to get a really smooth vibrato in the way that you would on a Prophet by nudging the performance wheel. The Korg tends to be more drastic – on or off. And it's hard to get really bright sounds. I've found that generally Korg stuff tends to be a bit dull sounding, same as the Poly Six, the filter stops short so you can never get that real sizzle."

So what sounds do you use it for on stage?: "Well, the Poly 800 has some great bass settings and a good full bodied lead sound... though it doesn't have the kind of penetration you'd find on a Mini Moog. When you switch on the built in chorus, that really opens up virtually every program you've got, and it's also good on muted string sounds. For what it costs, it's fantastic, not really that much less versatile than a lot of more expensive synths... but it can still sound Japanese... a bit characterless at times."

One of the economies that Korg seemed to have made is in the filter envelope. If you're holding down a chord and press down a new note, all the notes will sound again. Most polyphonic filters treat each depression individually: "That's right, it can be quite an interesting effect if you're playing rhythmically – it almost sounds like echoes. But it is a problem in terms of single line stuff; you have to be careful with your fingering. And there's no unison mode, it's always polyphonic."

What about the sequencer?: "It's not really that exciting. It is polyphonic, but you really have to know what you're doing in terms of leaving rests and stuff. It's not like you play and it remembers everything. I've mainly used it for bass lines and it's good enough for that, but it isn't a Rolls-Royce sequencer. It's also a bit fiddly. It's difficult to lean over and keep finding the right enable and disable switches on the back.

"The joystick is useful because you can select the increment by which it goes up or down. It's easy to make mistakes on a joystick because you can get carried away, but it's better if you can select a level – I suppose most people will be bending up by a tone or semitone to get the old 'wobble'. It's well designed."

How has it stood up to being shifted around on tour?: "Okay. They make hard and soft cases for it. It fits into your touring luggage, a bit like carrying a guitar. There's no built in speaker, but there is a headphone socket and I've been using a jack to mini jack adaptor for my Walkman headphones. I was doing some writing on it in Japan and over here. It's absolutely perfect for setting up in your hotel room."

£635