I meant why you can hear a difference in amps with the M9 and not with the Z1R.
Ah, i thought i explained it in the original post.
First of all, i can. It takes some time to be able to do that but its possible. But its not as easy and clear as with the IER-M9.
The IER-M9 is an 5-way 5-BA IEM while the IER-Z1R is an 3-way 2-DD 1-BA Listening In-Ear.
The IER-M9 has better drivers and, in addition to that, a tuning that allows to hear such things much better. It has an more neutral Tuning with much more midrange and a more linear treble with no peaks/dips.
The IER-Z1R is designed to sound big and wow and fun and clear and detailed. while the IER-M9 is designed to sound as accurate and authentic/realistic as possible. So the tuning alone already helps and an 5-BA soft-crossover Setup contributes to that.
Also it is an isolating In-Ear which means you hear much less (if at all) outside noise.
Its the Job of the IER-M9 to be good enough to detect minor differences in sound, that is what i was made for to begin with.
Most people think the IER-Z1R has more detailed because it has a more pushed treble and less lower mids, but most people confuse pushed frequencies with the actual amount/quality of details. Most instruments have most of their information in the mids. If you lower the mids and push the treble, you will hear some details easier you're not used to, but you have less details in summary. It is easier to concentrate and focus on what is there because there is less in total.
That doesn't mean the IER-Z1R is bad, not at all. Its almost perfect in exactly what it does, but what it does is not delivering an meticulously monitoring sound