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.

Here are the rubs. For one thing, it only seems to work well with circumaural headphones. I tried on-ear and in-ear headphones and it was vague and washed out and not a patch on straight-through stereo. Lucas worked best with the HD-580s I keep as a reference. (Surprise, surprise: Sennheiser sells the HD-580 with the Lucas in a specially-priced package.) Then it got down to two other things. The first is how much time you're prepared to invest in tweaking. The second is choice of material. Pure music wasn't even remotely enjoyable through Lucas, even with RCA's Dolby Surround audio-only CDs. In fact, it sucked, and every time I switched to conventional stereo, life was breathed back into the sound. More detail, greater clarity, more precision - it was as if the Phantom button meant what it said: it turned pure music into a bleached-out facsimile of itself.

But TV broadcasts, videos and laserdiscs were something else, possessing as they do artificially heightened directional information. It was just about possible to get the Lucas to act like a surrogate surround sound system for people with thin walls or nasty spouses, with relatively convincing directionality. But, friends, Lucas exists for only one set of reasons, the same ones which drive you to using headphones instead of speakers in the first place: late night use in flats and semis, bedroom use or while others are sleeping, ad nauseum. Better you should move or re-marry.

Lucas is like an electric carving knife. It seems cool at first, you want one though you don't know why, so you buy one anyway. And you'll probably use it once a year after the novelty wears off. Yet word on the street is that the usual toy junkies in the hi-fi community think it's the canine's cojones. Remember: even if it leaves you less than impressed, you'll still have a slick, afforable, pocket-sized Dolby Pro Logic decoder. Lucas only costs £279.95, while the Lucas/HD-580 package is only £454.95, for a £25 saving.

I just wish it wasn't named after the electrics which made owning old MGs and TRs such an risk.