Well, it is not just about impedance. You should look at sensivity either.

Can you let me know how or what I should be looking at to understand it better?

Your current device either cannot provide enough voltage into low impedance or you have some hearing problems.

Why can my KZ’s get stupid loud but the X’s at full volume are just enough with no room for more? What am I missing or not understanding. Could the X’s be broken?

1Vrms into 30 ohm is 33mW. Thus you get +15dB on top of the rated efficiency of 111dB/mW, netting you a whopping 126dB which will be PAINFUL.

The other one has its sensitivity given as 117dB/Vrms. So 1Vrms of output voltage will give you exactly 117dB

126dB > 117dB which is why one is louder than the other.

Both is more than enough to lose your hearing btw....

So, if 117dB peak aint enough for you, schedule an appointment with a doctor and check your hearing.

the kzs don't require much power to drive,that means you can run them off your phone without any trouble

the truthear × crinacle require more power to drive,which means that even at the same volume bar they will sound softer compared to the kzs

So maybe I’ll have to try the rear port on my PC where the amp is.

https://i.imgur.com/9EMnKnH.jpg

I was using the front mic/headphone jack so I’m guessing that’s the culprit and they aren’t being driven properly it sounds like.

Do you know if a 3.5mm extension cable (~3’) would ruin the sound in anyway?

This has been my experience. You’re absolutely right, it’s probably stupid that I was using the front headphone jack on my Pc and should try the rear port.

https://i.imgur.com/zdCFVWY.jpg

Looks like there’s an amp that’s helpful powering them. Do you think a 3’ 3.5mm extension cable from the back of the computer would hinder the sound in anyway?

The Zeros are power hungry compared to other IEMs, honestly I like that on my PC, I get more granular volume control.

The KZs are a lot more sensitive. i.e. need less power to get really loud.

The cable won‘t hinder anything.

What makes you think that’s where the amp is?

I suspect the headphone jack’s impedance detection feature is probably too “smart” for its own good and is artificially lowering the gain to get you more range on the volume knob.

I would caution against using the line out, it’s going to distort the frequency response with the Zero’s.

surprise; it's not just impedance

You’re correct! And I’m trying to learn about this hobby so do you have any cool info to help me out?

I’m sorry yeah I was just assuming the mobo has a slightly better output than the standard front panel jack. I’m still learning and trying to figure things out and kind of lost.

Well, understanding this stuff is basically a chapter of an introductory electronics textbook, so that's understandable.

The front panel jack connects directly to the motherboard. It's intended for headphones, so that should be the right place to connect them. It's possible the rear output will also detect that it's a headphone and connect it to the appropriate amp, but I think it's likely to have the same capabilities. There are also line-level outputs, which *may* give you more voltage than the "smart" headphone jack, but they can't drive much current so I personally I doubt you'd get better results with low-impedance IEMs. These audio chips are fairly complex, they mix multiple functions for each jack, and I don't think you can easily find a spec sheet for them, so unfortunately I can only guess.

So wouldn’t the front headphone jack that’s plugged into the mobo with a small pin connector be less amplified compared to the sound port that’s soldered directly to the mobo on the back of the computer where the audio chip traces to?

Nah, assuming the connectors aren't damaged/corroded, the electrical effect of that bit of extra wire is absolutely negligible at audio frequencies/headphone power levels.

>So my question is what am I missing,

Hearing...you're missing some hearing if the Zero is barely loud enough at max volume from your phone. You don't need an amp; you need to train your ears and brain to appreciate music at a safer volume.

Sorry I didn’t specify it’s being plugged into the headphone jack on the front of my PC. So your comment is irrelevant thanks anyways.

Just forget about the impedance with IEMs, its always very low. The sensitivity is the more important factor that determines how loud they play. A high impedance headphone can be easier to power than a low impedance pair if the sensitivity is high enough, your earphones are very sensitive so they require very little power to get loud, a pair with lower sensitivity requires more power, you regulate the power with the volume control which will need to be adjusted with each IEM to achieve the same level of loudness. A typical IEM has sensitivity about 105db/mw, an IEM with unusually low sensitivity like the Final E5000 has sensitivity of 93db/mw, the numbers may not seem like a big difference but it is substantial, one will play loud on anything, the other generally requires some external amplification.

The impedance of most IEMs makes very little difference to the loudness but, if you are getting a lot of unwanted noise with a very sensitive IEM you can use an impedance adapter which should tame it, I use an 80ohm adapter with one of mine, you need to really boost the impedance to get a substantial difference.

Impedance is how much resistance the speaker produces, sensitivity is how loud it gets given a certain amount of power. You could also think of sensitivity as efficiency.

Oversimplifying the math to illustrate this point - A headphone with a sensitivity rating of 75db will be about 75% as loud as a headphone with a sensitivity rating of 100db when connected to the same source.

A higher impedance headphone will typically sound worse, but not necessarily quieter (though often it's inherently quieter too), than a lower impedance headphone when connected to an amp that's not powerful enough to drive it. Think worse bass extension, less clarity. It still makes the noises it's supposed to but the amp is really struggling to control everything in the tight manner it's supposed to. The voice coil is also frequently able to generate a larger magnetic field from the higher impedance design, so if you've got enough power to drive it properly you COULD get better sound out of the higher impedance driver all other things being equal. The thing is they're never equal which is why there's not a "right" approach here, just tradeoffs to be made given what you're trying to accomplish.