Here is where you can run into a problem. When you have just a connector without the adaptor, the wire is tight behind your ear. With an adaptor attached, you extend the connector and make the loop around your ear bigger. Here how it looks using a dummy measurement “ears” from miniDSP setup. It’s a small model of the ear, but can give you an idea what I’m talking about:
Will it be a problem for everybody? Probably not. And it will also depend on IEM design. I do have smaller size ears. When I’m dealing with larger and heavier IEMs, like Solaris, I do need a tight over the ear earhook loop for extra support. So, in this case I preferred a direct connection without the adaptor.
Campfire Audio Solaris (stock Litz vs 1960 4wire):
But when dealing with CIEMs, like Westone ES80, or compact shell universal IEMs, like Westone W80, the adaptor didn’t bother me at all.
Westone W80 (stock Epic vs 1960 4wire):
Westone ES80 (stock Epic vs 1960 4wire):
And with a wire down, the fit will not be an issue, though you have to keep in mind about the cables with pre-shaped earhook since the wire will not go down straight, but often still works OK.
Once everything is connected and you are happy with a fit of the cable/adaptor pair up, the next question is the sound. It would be hard to do a true a/b comparison without knowing how it sounds without the adaptor. Fortunately, I had a pair of identical cables from Nobunaga Labs, both 2.5mm balanced, one with 2pin and the other one with mmcx.
This way I was able to do a true A/B comparison, to be able to hear how the cable with mmcx connector sounds directly in comparison to the same cable with 2pin connector and 2pin-to-mmcx adaptor. In this test I used SP1000 SS as my source. Below is a change in sound I hear when going from mmcx connector cable to the one with an adaptor.
Campfire Audio Vega – I hear mids/vocals to be a little more forward and have more clarity, and soundstage perception is a little wider.
iBasso IT04 – I hear mids/vocals to be a little more forward, and soundstage perception is a little wider.
Campfire Audio Solaris – I hear mids/vocals to be a little more forward, and soundstage perception is a little wider.
Based on this A/B comparison, I found no attenuation in volume, the tonality was transparent, and the only change I heard was a slightly more forward presentation of mids/vocals and wider soundstage perception in every pair up I tried. I guess you can even consider this as an improvement when using Rhapsodio adaptors with FIR isolation material.
I was looking for a cable adaptor to be able to test my 2pin cables with mmcx based Solaris IEM. Rhapsodio adaptor was the right accessory to get me there. It has high quality build, useful polarity marking, it’s short and compact, and it doesn’t color the sound. As a matter of fact, it even introduces a slight improvement in soundstage expansion which could be related to FIR isolation material used in the design. So, overall I found it quite useful.
But you have to keep in mind two things. First of all, considering its price of $100 per pair, it doesn’t make sense if you have budget cables that cost as much or less since you can just buy another “budget” cable with a different connector for the price of the adaptor. And second, you have to take into consideration that with some wire-up IEMs, adding the adaptor will increase the bend-radius of the wire going over your ear which can affect the look and the comfort if you have smaller ears, though this varies from IEM to IEM.
But in general, if you have a premium balanced terminated cable, you can make it work with any IEM and any source when you use connector and plug adaptors.