How about some Lambda Love on the thread? I've been listening to a 207 Basic, 307 Signature, 404 Sig, 404LE Sig and Lambda Nova Signature. I've got a Lambda Signature coming in too - reputably the thinnest diagram in the lineup (1 um), and the source of the supposed "Stax Etch". Am very curious to hear.
The 207 is quite thick and punchy. They're also accident prone. I got this pair by accident from PJ, and instead of sending them back he gave me a deal on them to keep, so I use them for test headphones with my new amps. They also had the only 'snap crackle pop' I've heard with Stax. Shortly after I got them, I'd take my eyeglasses off while listening and got crackling from it. Yikes! It wasn't moving around that much and I didn't poke anything. I think they don't get a lot of QA at the factory. But you get a helluva lot of Stax love even with these guys, I like the rough and tumble punch they give. They fit better than any of the others too, and the black looks better (plus it has a narrower no-nonsense cable). Probably good with a KGSSHV (will find out).
The 307 was my first Stax. Listening to it now on a KGST as I wring out the bugs (the amp graduated from the 207.) Not as thick and punchy as the 207, a clear step up. But it has lots of punch in general, and also a slight thick warm in a very good way. Great all around contender, I heartily recommend it for somebody looking for an entry into Stax. Does everything well and nothing poorly, good with any amp.
The 404 and 404LE are practically the same. Oh there's some slight, very slight differences, hardly worth mentioning. To be truthful I like the 404 a bit more. The difference between them and other Lambdas is refinement. They're more refined than the others, but with that they get more thin. That's the tradeoff, with all the Stax I'm hearing this sliding scale. But anyhow I like the straight 404 a bit more as it's got enough refinement without being too thin, and the 404LE goes just a little too far in the refinement/thin axis for my taste. At any rate for my music (classical) I like these the best of the Lambda's (I'm guessing the Lambda Sig will be even more in this direction). KGST probably a good match (will find out).
Finally the Nova. This is the warmest and thickest of the lot. So much that it ventures into getting 'blobby' and indistinct. I believe they did this in response to the Lambda Sig to fix the "etch" complaints from customers. Well they went too far in the other direction, and cleared it up in later headphones. Probably my least favored, but I listen to it when I just want some relaxing music, kind of like kicking back in a lounging chair to take an afternoon map. Don't try Rachmaninov with this headphone. KGSSHV would probably be a good match (will find out).
Just some notes on my thoughts about these cans from living with them.