STAX SR-009S/SRM-700S
There’s a saying about electrostatic headphones. It’s that once you’ve owned a pair, you’ll never settle for anything less. And in the electrostatic world, Stax earspeakers surpass all other designs in both sound quality and build quality. There are reasons for this. Firstly, Stax refuses to compromise on quality. Indeed this refusal to compromise meant that at one time its products were simply so expensive that their sales could not support the cost of production, and rather than produce a lesser-quality product, the company ceased production (in 1995) until support came its way in the shape of an injection of capital from Chinese headphone manufacturer Edifier. Stax also refuses to compromise its identity. By this I mean that having been manufactured in Japan since 1928, the company continues to insist that all products bearing the Stax name must be manufactured entirely in Japan: a nationalistic ethos that obviously increases production costs.
So what was the company to do when its philosophies meant that the price of its top-line electrostatic earspeaker driver, the SRM-T8000, crept up into the price-point territory that caused the company its financial woes a few years back? The answer is one of the subjects of this review: the SRM-700S. Whereas the SRM-T8000 is a valve-based unit, the SRM-700S is all solid-state, indeed it’s the first product Stax has ever manufactured that uses a particular type of solid-state device known as a J-FET, in its second stage (following low-noise dual FETs in the first stage). But the SRM-700S is also somewhat stripped-down in terms of features, because the more expensive SRM-T8000 has three switchable inputs, as well as a mute circuit.
But in creating a lower-priced unit, Stax didn’t want to alienate all those audiophiles who specifically wanted the valve sound that was inherent in the SRM-T8000, so at the same time it was designing the SRM-700S, it also designed a valve version: the SRM-700T. This unit is mostly identical, but 6SN7 valves are used instead of FETs in the second stage. As valve aficionados will already know, the 6SN7 is a medium-gain dual-triode designed in the 1940s that fell out of favour with circuit designers when the 12AU7 and 6CG7 types were released a decade later.
