Hey sorry wanted to get back to you earlier but never remembered when I had time.

IEM - Stand for In Ear Monitors. Basically a way of saying wired ear buds. Though while there are Audiophile "earbuds" which are what they call IEM's without a detachable cable.

The trick with headphones and IEM's vs. Their gaming and BT brethren is that creating and shaping the audio of a new driver can be pretty expensive. For IEM's thats the entirety of the R&D. For companies that have been around forever, good sound doesn't go bad. A DT990 or Sennheiser HD 600 have been around 30+ years because they were good for their job and never stopped selling. So you have the bonus of experience making drivers for the discerning ear you can build off your creations. With the counterparts, the driver is one of the last things to get designed. They might even design them every series or two because they have a new style or look and they need a driver that will fit it. But not only is one of the last, it might be ok if they put more resources into it but they don't put nearly as much as the sound guys. Even with the sound guys, you have manufacturing cost targets that might preclude using the best drivers. So for example. Sennheiser makes great wired headphones, and their BT stuff might be some of the better BT stuff, their BT stuff doesn't sound nearly as good as their wireless because even in manufacturing costs they need so much room for all the electronics and features. Meaning that you get one of their cheaper, easier to make drivers.

So anyways. My main point is one of these audiophile grade earbuds might be a great solution because they take up less space around your desk, good ones are solidly in your head, and tend to do better without an external amp.

MMCX is just a connection type. There are two solutions 1. 2 Pin, its a straight two pin connection into the cable. Less likely to break, but doesn't swivel (for better seals) and can be less secure to the bud (easier to fall out). MMCX is baised on the little wireless antenna's in your laptop connection where one side is captured like a bearing and it can swivel around. If you aren't careful when removing the cable you are more likely to damage one side or another and if its the earbud side you basically have to write it off. There are a lot of aftermarket cables for both. But with my MMCX with Mic cable, it was one of like 3 I could find. Much more out there for the 2 pin. You just need to pay attention to which type of cable it is when you purchase your IEM (assuming you do).

If you want to go this route give and want some suggestions at different price levels, feel free to PM me.