This is the Desert Island approach to synthesisers. If you were about to be stranded on a sandy Pacific atoll and could take only one keyboard, what would it be?

To save the agony of decision, Korg have fitted three options in a single case — a string machine, brass section and a 32 memory programmable polysynth, plus a flanger.

It wasn't always like this. The original Trident Mark 1 had only 10 memories on the poly and fewer features. The Mark II is a considerable improvement, catching up on many of the early flaws. The sound is undoubtedly massive. It has a real earthshaking bass end, and with all three sections running you could believe there's an orchestra, two rock bands and half of the Battersea dogs home under the bonnet. A lot happens.

Yet it still suffers from the nagging drawback that afflicted the first Trident. For two and a half odd grand you get a reasonable string machine, a reasonable brass section and a reasonable poly, yet individually, none of the sections is spectacular.

The polysynth in particular lacks details such as white noise, cross modulation, polyphonic portamento, unison mode and many of the smaller items that make up the subtle strength of pure polyphonic synthesisers. On the other hand it can play eight notes at once, now has a 24dB filter instead of the original 12dB and sounds fatter and more convincing on its own than the original Trident did.

There are probably more knobs on the Trident than on any other rival. The flanger at the left hand corner of the front panel accounts for four (depth, rate, manual and resonance), the delay vibrato system for another two and the individual volume mix controls for each section a further three.

That's before you get anywhere.

Taking the easy stuff first, the strings unit is at the far right, has its own attack and release controls, low and high eq (useful for eliminating some of the fizzy upper frequencies, but not all of them) and a gadget called "bowing".

This one's good. It gives each new note or chord an additional oomph in volume at the start of the attack, as if you were assaulting the strings with a bow.

Subsequent notes can be subdued in volume unless you lift your hands completely off the keys and start again. The string machine is smooth, the ensemble unit has no lumps to it and there are three footages: 16, 8 and 4 for the stratospheric stuff. Smart thinking from Korg since you never know where you'll be playing on the keyboard. You might still want a high string sound mixed in, even though you're at the low end of the Trident.

The brass gets a complete ADSR unit plus its own filter with resonance, cutoff and envelope amount controls. It's got a good range, though I couldn't always find soft, mellow brassings, and it usually had to be fed through the flanger to add some thickness. It's probably the Trident's weakest section, but still better than the majority of cheaper efforts.

The polysynth itself now has two ADSR generators for the filter and the VCA (the old version had only one) and both are punchy, giving the Trident some particularly gutsy organ sounds and a couple of snappy harpsichord and clavinet tones.

The extra fatness over the Mark I mainly comes from the additional bank of oscillators which can be detuned through a few semitones, but not through as much as a fifth which would help get weird chords and better bell and Chinese chime sounds.

The memories are divided into four banks of eight, are easy to get at, and the programming remembers your control settings in fine detail. Editing is a simple matter of moving the controls and alerting the synth to your intentions — no need to hit a separate edit button.

Waveforms stay the same as the original, ramp, square and pulse width. Gone are the piano one, piano two and clav presets. The extra memory space is far more valuable.

The keyboard splits 24 notes up from the bottom and each section can run the full length or over either half. A joystick control gives you up and down pitch bend to right and left; vibrato or trill when moved up or down. I always find joysticks less predictable and trickier to use than modulation wheels.

This Trident sounds big, slightly ballsier than its father and is definitely a drama machine, particularly when the flanger is swirling around the bass notes. It's less convincing for imitative stuff and won't mimic your pipe organs, string sections or choirs in quite the way that a purist polysynth can.

The most important department missing is the unison mode to convert it to a mono soloing synth. Korg might really be close to their keyboard that does it all. This one gets to 75 per cent.

£2599