XDA IIi-specific 2.5mm to 3.5mm earphone adapter wanted

[Bewlay Brother]

I have a bit of a problem... I had assumed that these types of adapter were all essentially the same until I began to notice that the sound quality on my recently purchased Shure SE310 earphones was lacking in certain areas compared to the standard-issue XDA IIi hands-free earphones. Problems include - high levels of hiss compared to the standard earphones (and no, this is not because the high end earphones are revealing more hiss in the recording - besides I create my MP3 files from my original cd's usually at 320kbits bitrate), mild sound break-up at certain upper frequencies, and even problems with the Windows Mobile Media Player GUI (screen display will behave oddly after a few minutes of playback - the scrolling track data info will suddenly speed up and the "pause" icon on the player will change to a "play" icon even during playback) - none of these occur with the standard headset.
Close examination of the original plug reveals the lower portion of the "stalk" is recessed... with an interior connection formed by the interior surface of the recess itself. This "extra" connection that the after market adapters I have seen so far FAIL to offer is formed when the plug is pushed home in the XDA IIi socket because, again if I look very closely, there is a small brass connection bit on to the OUTSIDE surface of the central stalk INSIDE the XDA. Now I have no clue as to what function this connection is but whatever it is - the lack of it on the "adapters" I have tried DEGRADES any audio earphones I plug into it AND causes a bit of weird behaviour with the Media Player GUI.
I appreciate that the standard earphones have additional functions such as volume control and send/end call and that these functions in turn would require additional connections in the socket... maybe the XDA is EXPECTING volume control circuitry when attaching earphones and this "orphaned" connection is causing the interference/break-up?
I would truly appreciate any help on this matter - particularly as I spent a small fortune on these replacement earphones assuming I was going to be able to use them to their proper potential...

[The Owl]

its not a straight 2.5 stero plug its actually a four pin one I know I bought one from HK as it turned out I didnt need it (now in my draw scratching its neather regions) with the P & P it cost me a fiver (GBP) but I believe Maplins also sell them now

http://www.maplin.co.uk/Search.aspx?criteria=2.5mm%204-Pole%20Plug%20to%203.5mm%20Stereo%20Socket&source=15&SD=Y

cost £1.99 plus P & P

[robsno]

I bought a cheap 2.5 to 3.5 adapter from ebay and it does not affect the sound only the different headphones you plug in make a difference the other puns are for answering/hanging up and the microphone.

[Bewlay Brother]

..after a lot of trial and error it seems the problem I thought I had is actually a different one. The adaptors are no longer the issue. Unfortunately the issue seems to be that the expensive Shure SE310's do NOT like having extension cords attached when used with the XDA IIi - even the one supplied by Shure themselves... adding this cord introduces some degree of high frequency break-up in audio reproduction that a simple pair of £20 Sony Fotopia earphones handles without any problem. I cannot explain how or why - if I swap the Shure ext cord for the one supplied with the Sony earphones I still have the same problem - if I plug the Shure earphones directly into the device (via an adaptor) without using the ext cord - all is well. The drawback being that the Shure earphone cord is way too short a length for my purposes, I do not intend listening to my music whilst holding the XDA practically under my chin.
In summary - my £20 Sony earphones are easier/quicker to fit into my ears, they sound better (there is a difference in mid-range - the Shures vocal reproduction is more up-front - the Sony mid-range is more laid back...) but overall it's plug-and-play compared to a lot of fiddling with the Shures - AND £130 cheaper. Where is the logic?