I noticed that Marv heard some mid-range shout with the LE as well.... I'm not really noticing it with my pair.    Maybe a little bit of a lift, but not a shout...

Yup you're right.. "shout" is a bit excessive but I think it's because I'm sensitive in this area and I think it's why I like the HD800 who has a dip in the 1-3 khz Area . Matter of taste I presum. 

There are a couple of factors that mitigate this: first, it's present in most stax cans - though to a much lesser degree in omegas; it's been part of the lambda sound since the beginning so if you like lambdas you've gotten used to it; finally it's not like the AKG 1-2khz shout, the 404LE still has very swift decay in that area. It's more noticeable over the long term, at least for me, in that lambdas tend to bring on listening fatigue faster than the omegas (which I can usually wear all day with no problem).

Which makes me really curious about the newer Airbow SC21, as it's a modified 507. If they can improve the 507 like they did the 404, I think it would be worth checking out for stat enthusiasts.

I really like even the stock 507, the SC21 does look tempting.

As for the sound differences between the 404/404LE, I think a large chunk of it is just the change in earpads. Then maybe binning on Stax's behalf.

There are a couple of factors that mitigate this: first, it's present in most stax cans - though to a much lesser degree in omegas; it's been part of the lambda sound since the beginning so if you like lambdas you've gotten used to it; finally it's not like the AKG 1-2khz shout, the 404LE still has very swift decay in that area. It's more noticeable over the long term, at least for me, in that lambdas tend to bring on listening fatigue faster than the omegas (which I can usually wear all day with no problem).

Two more hours of listening yesterday evening. I'm still a bit bothered by this mids.  Overally, I really like this 404 but during my yesterday listening ( Norah Jones  "The Fall" and Count Basie/Ray Charles "Ray Sings, Basie swings" ) I felt many time the need to lower the volume because of this feel of "shout".  I ended to stay at lower volumes than usually with my HD800.

Overally, As long as I don't compare to the HD800, the SR404 is quite fine and enjoyable. Comfort is so-so too.
 

Decided to bring my Panormaic Earspeaker stash out of storage and do some direct comparisons. My absolute favorite Lambdas are still the original normal bias one and the Lambda Nova Signature. The SR-507 in comparison is a bit too forward sounding for me, with less of that spacious vapory sound I love in the Lambda range so much. The tonal balance on the original Lambdas is delicious IMO.

The Sigmas though are just on another planet. Some of my favorite Stax ever, but definitely on the weirder side. They have a nice musical quality that reminds me a bit of Final Audio's Piano Forte models, though not as bandwidth limited and liquid-y sounding.

Definitive impressions on the Stax SR-404 "Signature" (not the LE)

- I used almost exclusively during 4 weeks while my HD800 was at colorware. . I never managed to forget the midrange shout. I really enjoyed the Speed and the overall clarity , but IMO this lambda sound unnatural. I had really good results with Electronic music where the speed really does wonders. I'm used to tight bass so I never felt those SR404 are so bass shy. that been said , those Stax definitely lacks of low mids and upper bass and the music seems to lack of foundation as if we listen too much  harmonics and not enough foundamentals.  The soundstage of the 404 is so-so too.  not as good as what offers a Koss ESP 950. weak layering, upfront presentation. definitely so-so.

During the period I tried a SR307 and I much prefered the 404. the SR307 has less midrange shout but more sizzle in the treble. I didn't like it enough to use it more than a few minutes. I tried an old Lambda pro signature too and loved what I hear. Huge soundstage , more clarity , uber detailed. great. Very quick try though so I can say more.

The point is when the HD800 was back home, I almost immediately stopped to use the lambda. it took me 10 minutes to readjust to the sound of the HD800 and then I forgot it to enjoy my music.

Conclusion :    . i sold the complete Stax combo so I stop my Stat experiences for the time being. will try later when i'll have enough money to play with Omegas or a good opportunity for an old lambda : Lambda pro et LNS.