With a little bit of patience and luck, I managed to get my hand on a Stax SR-Lambda Earspeakers, which is admittedly a bit rare, and expectedly so, since it was discontinued more than two decades ago. Introduced in 1979, it was a milestone product for the Stax Company, the first iteration of the Lambda series and the predecessor to all the Stax Lambdas produced after it, including the Stax SR202 Earspeakers which we have reviewed previously in this website. All the Lambda headphones owe their look and many of their designs to this original SR-Lambda. For this review, I am pairing the SR-Lambda with an almost as old Stax SRD-7 adaptor. The SRD-7, as the name says, is an adaptor which needs to be paired with a speaker amplifier to function properly. The good thing about it is that it is significantly cheaper than a full-size electrostatic amp, so you can get better bang for the buck. However, does this setup sound anywhere as good as the SR202?

I have been enjoying the SR-Lambda setup since the day I received it. Coming from the SR202, the sound didn’t disappoint me at all; it has all the electrostatic qualities I was expecting for. If you haven’t listened to a good electrostatic setup before, the first thing that will probably startle you when you listen to one is the sense of how clear everything sounds. One of my friends mentioned that after getting his electrostatic setup, his previous headphones started to sound veiled. He felt as if the singer that was singing behind a veil before has now come into the room and sang directly to him. This SR-Lambda also has that level of clarity, and there are several reasons why the SR-Lambda sounds so clear. The first one is just the nature of a good electrostatic driver, which is the excellent transient speed and distortion-less sound. To give you an example, listening to cymbals through the SR-Lambda, when the cymbal was hit, you know precisely when it was hit, and you can hear the clear and undistorted sound of the cymbal shimmering and fading into the background. Because each note is very well controlled without smearing on top of each other, it is also easier to focus, separate and listen to each instrument when the music gets complex. On many headphones, some instruments may sound more dominant and emphasized than the other, making it hard to focus on each. With the SR-Lambda, the instruments are voiced more equally in volume and there is an ample space and air between each instrument for them to sound distinct from each other. Even the K701, which is no slouch, can’t quite match the SR-Lambda in these areas. However, if you like long overhang and romantic decay like the HD650, you won’t get it with the SR-Lambda.

Another reason why the SR-Lambda sounds very clear is its realistic timbre. You hear some headphones described as metallic-sounding or wood-sounding (in a good way). I wouldn’t really associate the SR-Lambda’s timbre with an object. It is just simply clear and natural sounding. In terms of frequency response, the SR-Lambda is a relatively uncolored headphone. There is a certain liveliness to the sound, but it is more associated with the fast nature of the electrostatic driver than its frequency response. The only noticeable bumps are some punch in the upper bass and a bit forward midrange. The soundstage of the SR-Lambda is decent, quite wide but a bit diffused. Positioning of instruments is good, but the edge between each instrument in the soundscape is a bit blurred. On the good side, this wide and diffused soundstage might have resulted in the big sound of instruments. I was looking for an explanation on why orchestral pieces sound ‘grand’ with the Stax, and I found out that part of it can be explained by the fact that instruments just sound ‘big’ through the Stax. To explain, when I was listening to the Hippo Pearl (an IEM), the sound of an organ was about 3-inches in height playing in my head. When I switched to the Stax, the organ became bigger, about 7-inches in height reaching outside of my head. The organ’s sound on my DT531, which is quite big- sounding in its own right, was a little less than 6-inches tall.