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Not that £449/$900 for a set of headphones is cheap, when you consider that Sennheiser and Grado deliver miracles for under £100/$200. But there simply is no substitute for the open-back sound of electrostatics, the speed, the transparency, the detail, the quasi-out-of-head spatial characteristics. Equally inarguable is that electrostatic headphones have as distinctive a character as do serious in-the-ear designs from Shure and Etymotic, or over-the-top, wooden-bodied dynamics from Japan. If you've tasted the Stax sound and it pushes your buttons, then nothing else will do.

When Stax first delivered the oversized SR-Sigma Pro headphones, exactly 20 years ago, first reactions were hoots of laughter, if only because one looked like a complete schmuck when wearing such large boxes on the head. But for those thick-skinned enough to try them, the sound was revelatory. For listeners who despaired of the in-the-head sound of headphones, here was something that approximated speaker listening and the inescapably superior sense of three-dimensional space. (No, I haven't forgotten binaural, but this site isn't called Heroic Failures.)

Over the years, Stax has used the ear-encompassing topology in a variety of forms, models clearly aimed at headphone users who want the ultimate in sound rather than portability. Although there are rumors of hardcore Japanese audiophiles said to commute on the trains with Lambdas and Sigmas and later SR models, one must group them with the sort who have all-valve in-car systems. For the rest of us, if we're practical and sensible, there are two types of headphones: those for use in the home and those for use on the move. This system, not least because it requires mains power, is unashamedly immobile.

Stax's latest economy interpretation of the Sigma topology is the SR-202, and it possesses all of the traits of its dearer and elder siblings. It's a push-pull electrostatic ear-speaker with an impressive frequency range of 7-41,000Hz, and it will pump out 100dB should you wish to be a candidate for a deaf aid. With cable, this over-the-head design weighs 450g, another characteristic that obviates its use on the road.

Combined with this to create the SRS-2050 II package is the SRM-252II energizer. While the SR-202 headphones exhibit little beyond build quality to indicate any form of economizing, the SRM-252II is blatantly, er, basic, as the system name promises. Unlike the dearer solid-state or valve energizers, it offers nothing beyond the minimum: it drives only one set of earphones, its only control is a combined on/off/volume rotary and socketry on the back is reduced to two pairs of phonos for parallel input/output.

Which is not to say that it's rock bottom. I mean, how many Stax owners with deluxe energizers have ever driven two pairs of headphones at once? What kind of social reject listens through headphones with a guest? Doesn't that preclude the use of the word "friend?" (Please, no e-mails about iPod users who run their players with two sets of earbuds. I simply couldn't give a toss.)

Beyond the hair-shirt simplicity, it's a tidy box with external power supply, formed from an aluminum extrusion. Well-made, with a red LED to indicate on status and nice weighting for the rotary, it certainly doesn't shame the owner. Or Stax.

Although the input/output set-up provides integration with a separates system, I used it with sources fed straight in, rather than via a pre-amp, in order to hear the Stax system as purely as possible. Sources included the Musical Fidelity X-RAY v3 CD player, Rio Karma MP3 player and Nokia N95 mobile phone (with music encoded in AAC format). For comparison purposes, I used my trusty Stax SRM-T1W energizer and Stax Gammas and Lambdas.

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