Headphone Reviews

The bass response of the Pro Classic (and of headphones in general) was restricted to that which was fed directly to the ears. This restricted the sensation of real weight that comes from feeling the bass as well as hearing it. The ear is notoriously insensitive to bass—with loudspeakers that have the appropriate extension, there's an important tactile contribution from the skin's reaction to powerful bass wavefronts reverberating through the listening space. Even with modest loudspeakers, there can be more to this than you might expect. This can be a mixed blessing: the listening room's interaction with the loudspeaker more often than not muddles the bottom-end response, creating a garbled bass performance that's often worse than a lack of bass. But there's no denying that a good loudspeaker in a reasonable room can produce a visceral bass response that just can't be obtained through headphones.

This isn't to say that headphone makers don't try, but more often than not they just get a murky, thumpy mess. The Pro Classic is different. While it didn't flutter my pants legs or shake my booty, it did have an excellent bottom end—a bass foundation that needn't apologize to any I've heard with respect to clarity, detail, and openness, and that went very deep. However, with no "skin gain" and its resulting sensory impact, the bass did sound a bit tame and the extension was less obvious. At times the Pro Classic's low end sounded a touch soft, but this depended on the program material.

As I ran through my favorite bass-buster recordings, I was continually surprised at how deep the Pro Classic extended (as low as a good, full-range loudspeaker, if not a good subwoofer), yet they failed to give me goosebumps the way a loudspeaker with a similar range does. This may have been partially due to the Pro Classic's rather cool sound. This lack of a fully developed, completely natural warmth was much more evident when comparing the Pro Classic to other headphones than when listening to it by itself. In fact, it often came across as more of a contribution to that slightly distant, Lambda-family perspective than as a lack of mid- and upper bass. The clarity and definition of the upper bass were impressive, and contributed significantly to the already noteworthy sense of openness and detail.

My other specific reservation about the Pro Classic's sound was in its top octaves—a trace of fizz and fine grain combined with some low- to mid-treble forwardness. While this will be of little concern to most listeners, it will trouble others. One could argue that the Stax is simply ruthlessly revealing—most program material is not pristine, and some recordings were refreshingly free of this quality. But that doesn't explain my experiences with the Sennheiser Orpheus or the Koss ESP/950. The most expensive Lambda 'phones, the Signatures, share some of this treble forwardness with the Pro Classic, but it's slightly less pronounced, with the Signature's top end sounding noticeably sweeter.

It's hard to criticize the Pro Classic in any other respect. On the Chieftains' The Celtic Harp (RCA Victor 09026-61490-2), one of my 1994 Records To Die For, the result was, well, to die for. From the fine, subtle detail in the percussion to the airy, almost feathery sound of the harp chorus, the reproduction here was first-rate. While the bass was a bit polite overall and its impact and drive weren't up to those of reasonably good loudspeakers, it nonetheless faced the demands of the recording. The weight of the small drum was all there, and there was no mid-to-upper bass muddle or boom. On Mokave, Volume 2 (AudioQuest AQ-CD1007), the open, spacious top was accompanied by a well-extended, rich, yet clear bass. While the bowed double bass here again lacked the weight it has through a good loudspeaker, it still felt solid and had a natural, rosinous growl. There was some smearing of the hi-hat transients which wasn't really bothersome—that top-end emphasis was the likely culprit here. The overall life and sparkle of the sound grabbed my attention, and while I sometimes wished for a bit of a sweeter sound on orchestral recordings, it was never a distraction. It was as alive as reality demands.

The Competition
I was able to compare the Pro Classic with both the Sennheiser HD-580 driven by the matching HeadRoom Supreme headphone amplifier and the Koss ESP/950 electrostatics. When I reviewed the latter last year (Vol.15 No.12, p.158), I was captivated by its midrange performance, but I didn't think its response at the frequency extremes was quite up to the accuracy of the $2000 Stax Lambda Pro Signature. The Pro Signature's balance isn't much different from that of the Pro Classic, save for the Signature's more refined top end.

Compared to the Koss, the Pro Classic had a decidedly leaner, more analytical sound. The Koss's bass was richer and more full-bodied, though it didn't seem to extend any deeper than the Pro's. The midbass of the Pro Classic was tighter and had greater clarity, but at the expense of leanness—most evident on solo instruments and voices. I can think of no headphones, and few loudspeakers, that are as compelling through the all-important midrange as the Koss was. The treble forwardness and slight top-end fizz I heard from the Pro Classic were nowhere to be found with the Koss, though the Stax had a more sparkling top octave and an arresting sense of detail. In terms of perspective, the Koss was more forward and immediate, though not pushy, aggressive, or hard. Perhaps because of either this or the Stax's physical design, the Koss had a bit more of that "in-your-head" imaging quality. The more distant sound of the Stax, while not able to replicate the frontal soundstage of loudspeakers, did come closer to that more natural perspective. I'm inclined to favor the Koss's sound over the Stax's, largely because of the former's midrange qualities and the latter's more overt top end. But the Stax's openness and clarity can't be ignored.

And what of the Sennheiser 580 headset and HeadRoom Supreme amplifier? The Sennheiser is one of the more expensive, conventional (ie, non-electrostatic) models around. The Sennheiser/HeadRoom combination, which costs just under $750, is competitive in price with the Stax—though the Sennheiser/HeadRoom may also be used as a portable system.

The Sennheiser 580/HeadRoom Supreme was a formidable combination. Using it with all its bells and whistles (Audio Image Processor and Processed Frequency Response), I found that it gave up little or nothing overall to the sound of either the Stax or the Koss. But there were differences. The Sennheiser/HeadRoom, closer in overall balance to the Koss than to the Stax, was full-bodied—definitely more so than the Stax, but slightly less than the Koss. It was detailed and open, though it couldn't quite match the detailing and delicacy of the electrostatics. I also noted a hint of hardness in its sound, though this was a sometime thing and not at all irritating or distracting. Its deep bass was arguably competitive with the Stax's as the best of the group. The Pro Classic had the more open but also more distant sound; despite the image processing of the HeadRoom, with the Sennheiser 580 it came across as more "in-your-head" than the Stax, though somewhat less so than the Koss. In terms of overall balance, however, the Sennheiser/HeadRoom Supreme was the best of the bunch, though its margin over the Koss was slim—winning here by virtue of a slightly less rich midbass.

Conclusions
The Stax SR-Lambda Pro Classic had that distinctive Stax sound—detailed, open, and slightly lean, but with a striking sense of clarity and definition. It leaned to the analytical side of neutral, but did so in a way that didn't detract from its strengths. I definitely recommend it to your attention if you're in the market for a first-rate set of headphones. If you prefer to sacrifice a degree of openness to gain a more full-bodied balance, you need to look closely at the Koss ESP/950, the Sennheiser HD-580 (the latter profits from use with the HeadRoom amplifier), and perhaps the Grado HP 1s and 2s (which I haven't spent time with but which have a strong following). All of these (the first two from my own experience, the last by reputation) offered a warmer, sweeter sound than the Stax, but were short of the Stax's sparkling, detailed sound.