Question about Stax Lambda Pro Headphones

Thanks for your replies. It has been very helpful. I think I will stand pat !

Thanks for those links, Al. Man, I had no idea. I have to admit that those amps look very interesting. For now, I am content with my Stax amp; but.....

Back in the 1980s, shortly after the Lambda Pro came out, I listened to both and thought the Pro sounded too bright (at least to my considerably-younger self), so I picked a pair of the considerably-cheaper regular Lambda. I have not heard any other Stax phones since then. 

I still have them and am still happy with them, and have used them all these years via the SRD-7/mk2 hooked up to a variety of power amps. Back in the day, I listened to headphones a lot more than I do now.

Now it’s an occasional thing. With all headphones I get a tiny soundstage right behind my forehead, but other than that, I have always been happy with them.

This is probably an extinct product, but I have a 25-foot Stax extension cable. The Pro has a five-pin plug, the regular Lambda has a six pin plug. This cable has a six-pin female end, so you can attach it to any pair of regular or Pro Lambda earspeakers, and a spring-loaded 6th pin on the male end that will retract if you plug into a five pin socket. 

The danger is is that the retracting pin will let you plug your non-pro phones into a pro-voltage socket when using this cable. 

The SRD-7/mk2 has one of each socket on the front. I put a sticker over the five pin socket just to be sure nobody ever plugged my phones into the wrong one and fried them.