Fairly certain you will need one of the Audio Technica adapter boxes for sure. Got a re-terminated to TRS AT-706 here , same thing basically but it had been terminated in a TRS jack and absolutely useless in my fullsized A-X55 Dynamic Super-A Amp headphone out. ( I got them for driver swaps into a project it wasn't me that did that )
I JUST saw an adapter up on ebay a couple days ago ( a 706 box ) but could not find it again ( looked on .com,uk, .de). You see them from time to time though solo
....Unless these reterminated ones i have here are toast (usually if so they show imbalance these do not just very very low output on the TRS ) then the adapter box is a must ( and the ATH-7 has permissible input 500Vrms so....)
I see that those seem to have the same plug end as my 705's so a 705 small adapter, or the next size up 706 model with 2 ports, would be what you want judging by the look of your plug. ( smacks head here,, and of course the stock one that came with yours at one time )
Stax electret adapters use their 4-wire cable + 5-pin Stax plugs so won't work unless you find a female receptacle for the box or rewire somehow. Only 4 wires so fairly easy.
Funny though there is a BACK ELECTRET series under the later ATH-8 ( and others???) designation which is a different type than 705/6. The earlier 705/6 had a charged stator on either side of the diaphragm, where the back electret does a slightly different charged setup explained here for kicks http://wiki.faust3d.com/wiki/index.php?title=Electret_Driver_Principle
This back electret seems to be what yours looks like though the plug end looks like my older style as you can see here
Apparently the plugs are not compatible between newer and older ( they changed them from a DIN type to their own style ) but that plug is the same as my 705
I am trying to place your model it is not in the listings !
Have a peek here.
If I get around to swapping out drivers into the project soon, or at least a fast rewire to test, I will let you know if these are simply shot though I doubt it will be any good off a TRS. He must have used them some other way, possibly the speaker terminal directly with a female TRS is about the only other way. But I would NOT want to do that , since these are permanently charged membranes and you can possibly ruin them if your amp is goofy , and without the adapter transformers to regulate any goofiness.
Hope this helps and it didn't add to the confusion.
Edited by nick n - 5/28/13 at 12:03am