We knew that the SR-34 electret didn’t stand a chance against any of the Lambdas, which is a pure electrostatic design. But we couldn’t care less. Comparisons are always fun, and even if the electret SR-34 is inferior, we wanted to know how big the difference is. Both earspeakers were driven from SRD boxes. The Lambda was connected to the SRD-7, while the the SR-30 was connected to the SRD-4 (The SR-30 + SRD-4 combo is branded as the SR-34). If you look at the photographs, the SRD-7 that we used still have the vintage Stax logo, whereas the SRD-4 comes with the modern Stax logo. We take this difference as an indication of production dates, the SRD-7 being older, yet a higher end model in the line up than the SRD-4. Since the SRD-4 carries the label specifically for “Electret Earspeakers”, we didn’t want to try mixing the combination (such as the SR-Lambda to the SRD-4 or the SR-30 to the SRD-7), because lacking technical knowledge, we were afraid that some damage might occur.
The SRD boxes are not true amplifiers, in the sense that they require current from an external speaker amplifier to be able to drive the earspeakers. We happen to use the Adcom GFA-5802 power amplifier for this duty, since that’s the amp we happen to have at the moment of the comparison. From the picture, you can see that the combination may be an overkill, but who cares, it’s a lot of fun. Being a power amplifier, we need a method to control the volume, and so we used the Dr. DAC Prime for that purpose. Now that I’m writing this article, I feel so dumb for not using the Grace m902 instead, as it would be much better to serve as a preamp than the Dr. DAC Prime.
The actual source behind the Dr. DAC Prime was either an Ipod with a LOD to RCA cable plugged in to the Dr. DAC’s analog in, or the Apple Powerbook feeding digital data through USB to the Dr. DAC’s DAC unit. Since the Dr. DAC’s digital to analog conversion is much superior than the Ipod, the question then becomes, why bother with the Ipod? Silly as it seems, the Powerbook we have at hand have a rather limited music library, and the Ipod happens to hold a much bigger music library. In all, this may seem like a lack of preparation, and as a matter of fact, it was. We just came up with the idea to do this comparison the day before, and we didn’t really have time to set up a proper comparison equipment.