It looks like a large remote control, fed with a thick umbilical wire which provides it with the input signal and power. You stick headphones in the other end. Here, gang, is the first workable surround-sound-through-headphones device since the last stabs at binaural. Only this one's a product of the Dolby Surround era, so forget source material restrictions, like listening only to Flamenco CDs or crossover jazz.

Developed by American firm Virtual Listening Systems but marketed by headphone maestros Sennheiser, Lucas contains a genuine Dolby Pro-Logic Processor, VLS's proprietary Toltec DSP circuitry, full audio control and amplification for the cans - up to two pairs connected via mini stereo plugs. The incoming signal first undergoes regular Pro-Logic decoding and then it's fed to the Toltec processor. This stage generates five phantom channels to create a sense of surround sound through a pair of standard stereo headphones. Any home-cinema stereo line-level output will do, typically the output of a LaserDisc player or stereo VCR, and -- eventually -- DVD.

Lucas' brain is a Motorola Symphony 56000 DSP, a high performance 80MHz 24-bit chip. The unit is fashioned from alloy and its top surface is filled with press buttons to operate a bewildering array of controls, necessary to modify just about every aspect of surround sound you'd find on a 'normal' surround processor along with dedicated features which only have relevance to surround sound via headphones. The device is beautifully made and a joy to handle and operate; once you've read the owner's manual, you'll agree that the layout is sensible, too. Best of all, every operation is accompanied by a little 'light show' to tell you what setting you've selected. So don't let the 23 buttons worry you.

Oddest of the controls is the 'EARS' function which selects one of 15 generic ear shapes derived from the Head Related Transfer Functions; you settle on the one which positions the test tone 'centered in front of you at arm's length'. This is the core of Toltec's legerdemain; it's based upon binaural principles, and the subtle changes available from different ear mappings are so clearly identifiable that a session with Lucas raises concerns about every review ever written: if ear shapes have such a marked effect on the way sound is perceived or experienced, then how do we know when a reviewer is criticising a product or the compromises/deleterious effects caused by the shape of his own lug-holes?

These Head Related Transfer Functions are the product of precise coefficients which model the directional sound alterations caused by the head and pinnae. A DSP produces virtual 3D sound over standard headphones and the listener tunes the Lucas accordingly. And not just through the EARS control. There are numerous other parameters to define; setting up Lucas for convincing surround performance can take hours. 'Ambience' alters perceived room reverberation, while 'Seat' allows the listener to select a seat within the virtual room, and its effect is not unlike having your chair on rails moving fore and aft. A couple of preset positions allows Lucas to store two configurations and you can always revert to the factory setting.

Other functions include mute, volume, balance and bass, while the button marked 'Phantom' cancels all internal processing and allows you to A/B normal headphone stereo with the processed signal. A test tone cycles a signal to each virtual speaker, there's a separate set of volume controls for a second listener, and - this is the bonus - everything is included to turn the Lucas into a bargain of a Dolby Pro Logic decoder for your main system (i.e. through five loudspeakers), like mono/stereo/Pro Logic settings and ambience modes (theatre, hall and club) which you select according to their suitability for the source material. You simply feed the outputs to your pre-amp or integrated amp rather than to headphones for Dolby Pro Logic use, bypassing the Toltec processing. Stereo-mini-plug-to-phono adapters are included.

Remember: you don't actually hear five discrete channels when you set the Lucas to 'Phantom' and slip on your cans. What the test tones give you are distinct left/centre/right sounds, but the surround signals seemed - to my ears at least -more like ultra-right and ultra-left rather than sound at the rear.

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