I'm kind of cross-posting this on head-case. Soon after posting there I realized that this forum might lead to a more substantive discussion
I've owned a 404LE for a while and always wondered whether there were any differences to justify the differences in sound some observed in the LE beyond the cosmetics/cables. That is to say I suspected that it was a gussied-up 404 with sound similarity way beyond the simple lambda heritage. Which is fine by me, since before hearing it I thought of the Lambdas as some of the ugliest phones around, made worse only by the shit brown. So a sleek black headphone with terrific comfort and fit came as a welcome surprise and in my mind became ample justification for the price differential.
A unique opportunity to test my suspicions came about after Tyll graciously offered to provide stat measurements. Luckily, a regular 404 was in the sample group. The measurements of my 404LE as well as the regular 404 may be found at:
http://www.innerfidelity.com/images/StaxSR404S2742.pdfhttp://www.innerfidelity.com/images/StaxSR404LtdSSL0670.pdfHere's an overlay of the two freq. response curves, with the 404LE in the darker orange and brown vs. the light outlines of the regular 404:
The curves are nearly identical, except perhaps for slightly smoother & less rocky upper treble on the 404LE and maybe a slight improvement over the already excellent channel matching.
Where I did find a difference, and where it turns out it really might matter, was looking at the effect the different pads had on the isolation measurement (404 in blue, 404LE in violet):
Now is it possible that aside from the recorded linear/nonlinear distortion of the response that there is some added effect of having an essentially flat, little to no isolation measurement in an open baffle headphone? Could that variation in the upper bass/lower midrange section of the measurement explain some of the recorded opinions of varying bass response among the Lambdas? The fit and seal appear to play an interesting role in the sound of these rather large headphones.
Aside from the minor discrepancy between the two channels recorded in the regular 404's 30hz response the rest of the measurements are almost identical. (At least I think it's safe to say that minor differences in HD at decently less than -40db may be dismissed.)
The impulse response also looks to be within a reasonable margin of variation between pairs of the same model, though it's tough to tell without those lovely CSD waterfall plots.
Again, even though I don't see substantial evidence of 404LE having any notable audible differences from the measurements, the foundational sound of this headphone has been superb. Maybe I've a tendency to prefer a slightly brighter signature because the 404LE sounds fairly neutral.
