I personally use both MMCX and 2-pin connection IEMs. Regardless of they way my IEMs are designed, my main priority is getting the sound I want when listening to music. Despite this, the 0.78 mm 2-pin design is a common failure on many IEMs due to their thin size, non-reversable connection, and loose connection from wear and tear. After testing 100s of IEMs, I have to say I prefer the MMCX style despite owning multiple 2-pin IEMs. I was interested in the Leeds adaptor from Strauss & Wagner, to see if I could convert my 0.78 mm IEMs into MMCX connections without any signal loss. I'm going to share my detailed testing in the Strauss & Wagner Leeds review. 

Design

The ear-hook design is thin, comfortable, and easy to connect. The 8cm length is the perfect length for almost all ears. While testing with the Moondrop Aria II and 64 Audio U12t, I was worried that the 2-pin socket wouldn't properly connect with the recessed female port. To my surprise, they connected very snugly and there was no signal loss while listening. Because the 2-pin connection loosens over time, I appreciated the fact that I'd be able to keep these connected and feel confident the MMCX would extend the life of my IEMs.

When testing with the Strauss & Wagner Sion MMCX cable. The fit was comfortable, but I did notice that the earhooks wrapped back around my earlobes past the adaptor. This didn't impact the fit of the adaptor, but it took some getting used too. If you're buying a cable along with this adaptor, I'd suggest a flexible cable without earhooks if you can. 

Listening Impressions

I typically judge adaptors based on how little they effect the rather than what they add to the sound. There was the same fidelity increase and more highs that I expected from the S&W Sion cable. These adaptors didn't cut out or hiss due to poor connections. They're easy to wear and didn't change the sound of the IEMs used or the cables. Soundstage wasn't negatively impacted by the adaptor, and I actually got more separation from the Aria II in my testing.

Conclusion

Adaptors aren't supposed to color your sounds and their main function is to transfer signal without any changes. The S&W Leeds adaptor does just that. It's comfortable, easy to connect, and transparent. If you're drowning in different cables, using an adaptor is an easy way to make specific cables multi-use. 2-pin connections are frequently a failure point and will loosen over time. An adaptor like this can not only extend the lifespan of the connection, but also reduce the amount of extra cables you'll need to carry around in order to enjoy your IEMs.

You can get the S&W Leeds at Audio 46