To try and explain my reasoning here, in this 6moons review comparing the 303 and 404 the reviewer stated:
"lengthy listening netted no reliably discernable differences with this recording, certainly none in frequency response, tonal balance or overall presentation."
He goes on to try and find a difference and comes to..
"Only in the electric sarangi, an Indian bowed cello, could one again imagine to spot the 303's ever-so-faint damper on transient bite. Was I to pronounce the Classic a marketing mistake - far too close in performance to the Signature to successfully sell the latter; way too much applied trickle-down technology to flush the foundation of superiority out from under the 404 with a Biblical vengeance? I needed audiophile-approved high-resolution tracks to be extra sure."
To me, this sounds like someone thinking themselves into there being a difference and I rather trust his first impression that there was none.
Reading through the mammoth Stax thread here I found several mentions of them basically being the same driver with a different cable.
When the 507 was released I found a few mentions of it being the 407 with leather pads, and even the Stax page says the 307, 407, 507 share the same "element" whether that means diamphram or the whole assembly I don't know.
A big thing for me is when I bought the EP507 and stuck them to my 303 - now I fell in love with Stax listening to the 507 at a meet and the sound had really stayed with me, when I put them on the sound changed radically - it makes them sound much closer to the 507. The extra bass, clarity, reduced mid-bass, crisper highs. Not as good as the 507 as I remembered it, but my guess work has been that its the same difference in quality as between the 303 and 307.
So while in my mind it was confirmed - I guess I had just made the deduction about the 404LE.
Yes, the 404LE sound very different to the 404. The 507 sound very different to the 407. The 303 with the same pads sound very different to the 303.
Those pads really do change the sound.
My intention, when they get to the right price in the classifieds, is to get some 307s and put my EP507 on them - I am willing to bet (not all my worldly possessions, but a sizable bet none the less) that I will basically have a 507 with a lesser cable and different headband and colour scheme.
Edited by EddieE - 6/10/11 at 2:31pm