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Two thousand and seven proved to be a busy year for Marshall, with two new designs in the KT66-powered Vintage Modern series and this all-new flagship, the JVM 100-watt head.

The JVM's cabinet and styling are what we've come to expect from Marshall - the word 'iconic' is over-used these days, but nobody would argue that it shouldn't apply here. Heavy-duty hardware combined with black vinyl, gold control panel and the famous white script logo produces a reassuring presence that will make any guitarist feel right at home. The JVM's deep steel box chassis is home to a lot of electronics, and as you'd expect from an amp with 28 knobs on its control panel, these are all mounted on printed circuit boards.

One very big PCB holds all the preamp and power amp components, including the valve bases and most of the rear panel items, while three more support all the front panel controls. The main board is through-plated and all the components are typical of Marshall's high quality standards. With such a reliance on PCB layout, internal wiring is minimal but what there is has been neatly routed.

One benefit of this type of construction is built-in consistency - gone are the days when you could tweak a Marshall just by repositioning a few wires inside the chassis. However, this construction means the five ECC83 preamp valves are deeply recessed and will be tricky to replace in a hurry.

The reason for such a densely populated control panel is that the JVM is a proper four-channel design, with four sets of gain, volume and tone controls for each channel. Furthermore, each channel has a mode switch that offers three distinct voices with varying amounts of gain, giving no less than 12 preset sounds to play with. There is a digital reverb with a level control for each channel, two switchable global master volume controls and presence and resonance controls to fine-tune the power amp's high and low frequency response.

Moving to the rear panel, there are no less than five speaker outlets, two effects loops (one series, one parallel), a balanced speaker-emulated line out, which works in conjunction with the front-panel standby switch to offer a silent recording mode, a footswitch jack for the included six-button stage board and a pair of MIDI sockets.

Yes, the JVM is MIDI compatible so any MIDI effects unit can track program changes, or send program changes to the JVM. But that's not all. The non-MIDI stage board is also programmable - you can use it to either duplicate any of the front panel switches or recall entire channel presets. Every time you change a function the amp remembers this setting so, for example, if you select the crunch channel in red mode with reverb and the switchable master volume engaged, that's what you'll get the next time you return to that channel.

Marshall has deliberately left each footswitch button with a blank label, so you can work out your ideal set-up and then write the various functions on it yourself. Furthermore, this board isn't connected using an expensive multicore cable; any two-conductor lead up to almost any length will do the job. It's a very clever and logical switching design, making what seems at first glance an intimidating amp child's play to operate.