The SR-L700, like almost all Stax earspeakers, is an open-case design. That means it does nothing to attenuate outside noise from reaching your ears—or from your music reaching the ears of those nearby. For all practical purposes, the SR-L700 is for listening at home in a quiet, private environment. If you need isolation and portability the SR-L700 is not your best option.
The SR-L700’s cable is permanently attached. If you need a longer cable you can purchase extension cables from Stax. I have a Stax 25-foot cable that I’ve owned for more than 20 years, which I occasionally use if I want to pace while listening. It’s still as good today as when I acquired it. I know cable-rolling fans (those audiophiles who like to try third-party cables with their earphones) will be disappointed that they can’t use alternatives to Stax’s stock cable. But the stock cable is so remarkably rugged that even a cable-roller should be content. I have been unable to nick, crimp, twist, or irrevocably bend the cable on my Lambda Pro Nova ear speakers, even after many years of use.
The only aspect of the SR-L700’s physical design that makes me nervous is the plastic yoke that holds the Lambda enclosure in place. It is pretty much the same yoke that Stax has been using for its Lambda Series for the last 36 years. And even on the thinner original Lambda enclosure, the yoke was flimsy and barely adequate. Over the years I have purchased several replacement yokes for my Lambda Pro Nova headphones because they cracked and broke. I suspect that using this same yoke material and design on the SR-L700’s will have similar results. I recommend handling the SR-L700 with extreme care to avoid broken yokes.
The first time that you hear a pair of Stax electrostatic headphones, regardless of model or manufacturing date, the primary impression they make, if distilled down to a single word, is speed. The transient response of a Stax electrostatic design, when compared to a more conventional dynamic driver design, seems “faster,” with less additive distortion stemming from the mechanical action of the driver itself. With its lower mass, an electrostatic diaphragm moves with less physical impedance and once in motion can stop with less electronic damping needed because it has lower mass than a comparable dynamic driver.
After listeners have spent some head-time with a pair of older Stax Lambda headphones, the second thing that many will notice is the ’phones’ unique bass character. The Stax low-frequency presentation has always been airier and faster than other headphone technologies, but many of the earlier Lambda models lacked impact in what I refer to as “the meat and potatoes” upper bass and lower midrange region. The only older Stax model that had enough midbass weight for my tastes was the SR-X Mk 3. The SR-L700 is the first Lambda model that delivers satisfying weight and impact in the lower midrange and upper bass. While it still may not deliver enough low-end impact for serious “bass-head” EDM fans, the SR-L700 definitely offers enough bass to keep anyone who prefers a balanced harmonic presentation happy.
The size and image specificity of the Stax SR-L700 soundstage is dependent on the driver unit that is attached to it. The tube-based SRM-007tII produced the largest and most precisely imaged soundstage, followed closely by the older SRM-007t, which is also tube-based. The smallest and most congested soundstage resulted from the oldest solid-state driver amp, the SRM-1 Mk II. The current-production solid-state SRM-727I’s soundstage and harmonic characteristics were definitely superior to the SRM-1 Mk II’s, but not quite as precise or expansive as the two tube-based driver amps.
Using different driver amplifiers with the SR-L700, I quickly discovered that these earspeakers do “scale up” nicely. By this I mean that when you tether them to a better-performing drive unit the SR-L700’s overall fidelity improves noticeably. As a result, audiophiles who can’t afford the SRM-007tII amplifier will not be hearing the SR-L700’s full sonic capabilities. However, unless you do direct A/B comparisons between amplifiers as I did, I doubt you will find the SR-L700’s sound to be sub-par with any amplifier, including the “lowly” SRM-1 Mk II (which you can find used for around $300). The primary sonic issues with the SRM-1 Mk II are that it had a darker tonal balance and smaller soundstage than other drivers I used with the SR-L700s.
The SR-L700’s new stator design is more efficient than that of the older Lambda design, and at any volume setting the SR-L700s will play louder than the original Lambdas. This increased efficiency came in quite handy with some of my own live concert recordings, which were recorded at lower levels than commercial releases to allow for their wide dynamic range. With the Lambda Pro Novas I had just enough volume using the SRM-007tII turned up all the way, but the SR-L700’s additional sensitivity let me ease up some on the volume knob setting.
During the time I was listening to the Stax SR-L700 I had the new Audience 1+1 V2 speakers installed in my desktop system. Comparing these two seemingly very different transducers, speakers-to-headphones, was enlightening. Both are crossoverless designs that have a more cohesive and well-integrated midrange presentation than a transducer that needs a crossover in its upper midrange (which is where most two-way loudspeakers have their crossovers). But even when used nearfield, my room added some additional midrange energy to the original signal coming from the 1+1 V2 that was absent from the Stax SR-L700’s feed. This illuminated one fundamental truth: If you want to hear how a recording sounds without any room colorations, use headphones. Any loudspeaker, even in a nearfield setup, will interact with the room in ways that will have an audible effect on the overall perceived harmonic balance and presentation. If you need to hear how a recording sounds without room colorations, a pair of SR-L700s is a great way to go.