I'm relatively new to this whole audiophile world and I don't understand a lot of concepts but most above all is the impedance/matching Impedance stuff, so i was hoping someone would help me out.
Impedance matching is most commonly just to have the load impedance (the nominal impedance of the headphone/IEM; or speakers) being roughly 8X the output impedance of the amplifier circuit driving them. This ensures that the damping factor ie how well the amp circuit can control the movement of the transducer will not be reduced. This is a very general rule however because:
1. If the damping factor is very high and the impedance ratio doesn't necessarily drop damping factor drastically then you'd still have reasonable control over driver movement.
2. This is more applicable to dynamic drivers than, say, balanced armature drivers. This is because the pumping movement of a dynamic driver is a relatively more violent movement where the diameter of the driver and how far it can pump can lead to issues and compromises, and using several different driver types (dynamic or not; or a mix of different drivers) is not a much easier solution since you'll have crossover ie transition ranges between each driver where you can have other problems.
There are other concerns for matching impedance as well but involves other factors. For example, amplifier output varies depending on the load impedance depending on its voltage and current performance, so you need to mind how much power you can get. This is typically not a problem with IEMs and dedicated amp circuits due to relatively high sensitivity of IEM drivers, though of course there can be some exemptions; but generally most of them wouldn't have a problem even with the 5mW out of some mobile devices' integrated audio chip (ie DAC and driver circuit in the same chip, which, in the case of Snapdragons, is integrated into the chipset; that would be kind of like most Intel CPUs that actually APUs but they don't use that term while 15mW chips not hobbled in software for battery life tests by reviewers is more like an AMD Bulldozer APUs or more recently those with Vega chips; while DAPs will be more comparable to AMD RX 6000 APUs with RDNA graphics).
Another is amp stability ie you get distortion and heat that will destroy the amp, but this is far more common with speakers. Home audio amps for example can be unstable below 4ohms, if not below 6ohms; car audio amps are designed for 4ohms, typically; but home subwoofer amps are designed to drive 4ohm to 2ohm loads while car audio subwoofer amps are typically designed to be stable to 2ohm if not 1ohm loads. A more common concern in personal audio is when low impedance drivers also have high sensitivity - whereas you may not have a problem with distortion since you also won't crank up the amp, it also adds noise, which is also a more common issue in personal audio primarily due to driver proximity to the ear drum (many decent quality speaker amps actually produce audible noise, but you don't listen standing right next to the speakers to hear it) as well as isolation (most lower range HT receivers are actually horrible with this, but these also tend to be in a living room, not a dedicated theater room; it's not until you factor in other amp characteristics and have it lose to a stereo amp with half the power that all those issues combine into a Captain Planet of bad sound quality) where an IEM isn't just closer to your eardrums, it'll also block a lot of external noise that in say a living room HT system would just blend into the ambient noise unless you stand next to the speakers.
Will my Thieaudio Monarch mk2 be drived by my phone (S20U) or my DAC (M-DAC Nano)?
The Monarchs have Impedance 36ohm and Sensitivity 108db, while the dac has Matching Impedance (Ohms) 8 to 300 (Ohms)?
The Monarchs have a relatively high nominal impedance. It won't be a problem for amp circuit power delivery, just relatively high in the sense of it not being typically a cause for concern as it's even above 32ohms. Sensitivity is also not very high, so while it will require way more power than, say, a Westone2, it's not a decent smartphone with 15mW of power will have a problem getting it loud enough and not clip some louder notes.
That said...your smartphone can't drive it. Not because its audio chip sucks or that it doesn't have one, but because Samsung thought you shouldn't be able to hook up an IEM to it in the first place. And yet that thing does have a DAC in it, just that the driver stage of that DAC powers only the internal speakers so you can show somebody a cute TikTok with audio (yeah that idea that the 3.5mm or even just putting a 2.5mm jack in there being a problem? That's BS, because it's not like the space for the traces and 3.5mm jack went to something useful like a bigger battery).
The M-DAC though would have enough power for it. Stating it has an impedance range of 8 to 300ohms doesn't really tell you anything though, because that's like saying a Toyota 2.4L engine can be used to power anything from a Camry to a Tacoma, which doesn't actually mean that the Camry can hang with an Acura TLX Type S or that the Tacoma can't pull a boat on the freeway on the way to the lake or beach as easily as a Chevy with a Duramax Turbo Diesel producing upwards of 600lbs/ft of torque. However, it does say it's got 30mW at 32ohms. That's not a lot, but 1) that's still enough to get those IEMs loud (without raising red flags as to the possibility of it clipping or distorting easily) and 2) it's tiny, so that's more like having a 400cc twin in a motorcycle. It's no F3 nor F3 Brutale, let alone an F4, but you don't buy something that small for outright power, you buy it for portability.
