As far as the technical definition and parameters of
dynamics go,
@Liberatus pretty much covered it in full. When it comes to how it's heard in an IEM, I believe I've talked about it on Nic's thread some time in the past, but I'll do so again here. Though dynamic range can technically be measured in terms of dB, when I say an IEM has "great dynamic range," I'm referring to its ability to go from
soft to
loud;
laidback to
thunderous.
The easiest way I personally determine this is to use a track that builds as it goes on, like Snarky Puppy's
Go. The arrangement builds with more instruments thrown into the mix and the whole ensemble growing louder each time. An IEM with great dynamic range should be able to portray that build properly and convey a proper crescendo by the end. Another tell-tale sign is that those IEMs will seemingly sound "empty" when these arrangements first start out, and they'll only sound "filled out" once the arrangement reaches its climax, whereas an IEM with poor dynamic range will sound packed from the get-go and "choke" by the climax. This is quality that I think EE's Odin truly excels in. Heavily-compressed tracks with little dynamic range will sound like packed, scrunched-up balls in the middle of its vast soundscape, while more dynamic-sounding tracks fill its space gorgeously. That's the broader term I'd use to describe
dynamic range, and there are probably quite a few nuances I'm missing here, but it is what it is.
Macro-dynamics to me determine an IEM's overall sense of punchiness; slam, power, etc. It can come from any part of the frequency range, though it's most commonly rooted in the extremes. It's why v-shaped IEMs tend to sound punchier than most, but the compromise there is obviously going to be midrange fullness and presence. Th extension of the lows and highs, to me, play a much bigger role than quantity in that regard, as even IEMs with relatively neutral amounts of both can sound punchy when properly extended; say, 64 Audio's A18s. Conversely a v-shaped IEM with less extension, such as Nocturnal Audio's entry-level Avalon, will eventually sound dull following the initial
wow first impression. With that said, midrange macro-dynamic energy is also crucial for, say, brass sections in a
big band setting, where horn stabs can be relied on to drive the arrangement. And, the same applies to rhythm guitars in rock, or belters in ballads. Macro-dynamic energy I think is what separates sounding
punchy from just sounding
loud, and it's a broader form of dynamics that one
can achieve with shortcuts like, as I said, tuning a v-shape.
Now, micro-dynamic energy is what
@mvvRAZ is talking about with regards to a black background. To me, micro-dynamic energy is an IEM's ability to make background sounds and micro-details
pop, and a stable, black backdrop is required to do so. Otherwise, those little nuances will just blend into the backdrop and never catch your ear. It's a hallmark of high resolution, and it's less crucial for genres like modern pop, where those micro-details have been brought forward through heavy compression anyway. But, it's
crucial for genres like classical, where tiny bells and chimes and choir parts here-and-there all play integral parts in weaving together the story the piece is trying to tell. With those little nuances missing or blending into the "noise floor", I often find those pieces lack emotion; ending up sounding - again - dull.
It's also crucial in a genre like jazz. You can find a great combination of macro- and micro-dynamic energy on Robbie Williams' cover of "I Wanna Be Like You" with Olly Murs. Great micro-dynamic range is required to portray all the rises and falls of Williams' vocals - his little inflections and purposeful shifts in power - to convey the playfulness and fun he's trying to evoke through his performance, which perfectly fit the lyrics and vibe of the track; again, the story it's trying to tell. This'll be a talking point on my FiR M3 review, which is coming soon, by the way.
And, where macro-dynamics come in is the contrast between the quiet, almost
sneaky vibe at the start of the track, versus the uproarious, horn-blaring climax. Taking the two together, you get all the joy and glee the track is asking for, and - in my opinion - what everyone involved in making it intended to convey in the first place.
Again, writing this off the top of my head, there are probably nuances here-and-there that I'm forgetting. But, that's the gist of what I've found
dynamics to mean for me.
