Musicians who play both guitar and electronic keyboards face something of a dilemma when it comes to choosing amplification. On the one hand there are few - if any - amps with inputs capable of doing both instruments justice, while purchasing two separate combos is both expensive and, for many people, impractical.

Now Japanese giants Korg have introduced the MM-25 Multi Monitor, a portable combo amp designed to match the same company's KMX-8 mixer reviewed in last month's E&MM. The unit shares the mixer's composite metal and plastic construction and matt grey finish, and is built to the same robust standard.

Like all combos, the MM-25 can be divided into three main sections: pre-amp, amp and loudspeaker. The pre-amp section seems conventional enough at first glance, with two inputs positioned to the left of the unit's front panel. The first of these is a straightforward line input with an impedance of 50k, but it's the second socket (marked 'Function') that provides the greatest source of interest.

Essentially, the function input's impedance level can be selected from a choice of six settings provided on a rotary control above the jack socket. First of these is a mic input with an impedance of 10k, followed by Guitar, Distorted Guitar and High Keyboard (all 500k), Low Keyboard (also 500k, but with 10dB less gain), while last of all is a Line input with identical specifications to the separate jack described above.

There is of course an overall volume control governing both jacks, though sadly no individual mixing is provided, making level matching possible only by controlling whatever controls are present on the instruments in use. There are also two tone controls, Bass (operating at a fixed frequency of 100Hz) and High (10kHz). Oddly, these controls have entirely different cut and boost parameters, the bass pot being capable of a maximum of 10dB boost and 15dB cut while the treble can manage 14dB of boost but only 8dB of cut. However, while this looks more than a little strange in the context of a spec sheet, in practice both functions work well enough, though in these hi-tech times of graphic equaliser-equipped amplifiers, the facilities of the MM-25 are perhaps a little basic in this respect.

Lastly, the pre-amp section has a Line Output for connecting a second MM-25 (to make up a stereo pair, say) or side-step the need for miking-up when recording.

The main amplifier is specified as having an output of 25 watts rms, 50 watts peak, though when the amp is pushed towards its (not inconsiderable) limits, it sounds like rather more. The amp drives a single full-range speaker of 12cm diameter, the latter presenting a load of four ohms.

A bass-reflex vent is located at the top of the unit and this (together with the amp's solid construction, I would guess) assists greatly in giving the MM-25 that solid, clean and undistorted sound that so many other Mini-Monitors aspire to, but never quite manage to achieve.

With the possible exception of the Mic input, which has perhaps a little too much gain for its own good, all input functions were dealt with admirably by the MM-25, Distorted Guitar being the most impressive given the limitations imposed by the unit's size and power. It's no exaggeration to say that the Korg confidently out-performed many combos of twice or three times its size, and this is particularly impressive when you consider that, as hinted at earlier, many of its competitors are considerably less versatile when it comes to handling different types of input.

As if to emphasise the MM-25's versatility, Korg have provided the output section with two headphone sockets (both with an impedance of 32 ohms), one of which cancels the output of the loudspeakers completely - so now you can blow your own brains out with an overdrive guitar solo and still be on friendly terms with your neighbours.

As an all-purpose monitor, the Korg MM-25 is (to my knowledge, at least) more or less unequalled in the confidence with which it deals with almost any situation that might arise. Subjectively, it adds little character of its own to the input signal (again, with the exception of the Mic input), and its signal-to-noise ratio is extremely creditable at better than 75dB with volume at maximum and tone controls flat.

No reverb or chorus unit is provided, but this would be out of character with the MM-25's possible functions as a home studio active speaker or as an accurate (and forceful) on-stage monitor for live work. The unit is usefully light at around 5kg, and a built-in foldaway handle makes it all the more easily portable.

For those on tight budgets (or for those who are undecided about precisely which sort of monitoring to plump for) the MM-25 begins to make an awful lot of sense, and my only gripe is that Korg have not fitted any form of 'EQ cancel' switch to bypass the tone controls completely, which would make the unit that much more suitable for studio monitoring (in stereo pairs, of course). Yet as it stands the MM-25 is still an impressive piece of hardware, and I only wish other manufacturers would follow Korg's example in providing a monitor that really can be used in virtually any situation.

Recommended retail price of the MM-25 is £159.95 (inc VAT). Distribution is by Rose-Morris, (Contact Details).