Stax Sigma high frequency response

[SteveFord]

I have a set of Sigmas from the early 80s (I'm the original owner) with the SRD-7 adaptor box.
Compared to my AKG 701 or Beyerdynamics 880s the output is very low and the high frequencies are really rolled off.
Can any Sigma owners tell me:
Is that just the way these headphones are?
Is it the adaptor box? or
Are my headphones in need of service?
 
I don't remember them sounding this way but it's been quite a few years since I've used them. 
Are there any Sigma owners in the Baltimore/York, PA area?  Maybe I could try a comparison to see if my headphones are screwed up.
Thanks in advance,
Steve Ford

 

[John Buchanan]

Steve, the Sigmas do have a reasonably marked high frequency roll off. If you like the sound otherwise, consider a 404 driver and cable replacement for the stock Sigma drivers and cable. The high frequency response is vastly improved and vocals are still not sibilant. It isn't your SRD-7.

 

[SteveFord]

Yes, I do like the basic sound.
I'm the US so does anyone have any recommendations for the driver and cord?

 

[gilency]

What John said. Any Pro bias cord will do. 404 drivers will improve your Sigma.