Physically, Classic Keys is slim, black, 1U high, and well built. It features the dreaded parameter/value programming system, but it's a pleasant surprise to find that, thanks to the clear and simple front panel, it's a doddle to program and use.

CK is based on 8Mb of samples drawn from the Emulator III sound library, and uses these in place of the 'oscillators' of a conventional synth. Unfortunately, there are no filters, resonant or otherwise, to modify the sounds so, whilst you can apply envelopes, LFOs and effects, you cannot alter the samples' fundamental tones. This means that, despite the module's name, you can't duplicate any fashionable analogue filter‑sweeps and bleeps unless there is a sampled waveform which already features the effect. Nevertheless, with hundreds of samples to choose from, 512 patch memories, and a whole bunch of effects to pass them through, there are bound to be enough hidden goodies to make life interesting.