How can a paranoid man be sure that his DAC/AMP won’t blow up his IEMs?

[unpluggged]

I feel like a broken record at this point but here goes:

The Apple dongle has a base gain/output voltage of 1.0Vrms

Both Apple dongle versions default to -20dB UAC2 hardware volume.

If your OS does not natively support UAC2 Hardware volume control (e.g. Android or Windows 7 w/o custom drivers), then you'll be stuck with this 20dB reduction unless you can inject UAC2 control, using programs like USB Audio Player Pro.

The EU Apple dongle has an additional -6dB attenuation built-in, which can only be disabled by an Apple OS.

So:

EU Dongle

	w/ UAC2 Control	w/o UAC2 Control
Apple OS	1.0V	doesn't exist
non-Apple OS	0.5V	0.05V

US Dongle

	w/ UAC2 Control	w/o UAC2 Control
Apple OS	1.0V	doesn't exist
non-Apple OS	1.0V	0.1V

Additionally:

-Google have announced they will fix the lack of UAC2 volume control in upcoming Android versions (not necessarily implementing full UAC2 volume control capabilities, but at the very least forcing 100% UAC2 on startup so that the -20dB default value no longer matters)

-not all Apple OSs will unlock the EU's -6dB limiter, there's some shenanigans going on with iOS. MacOS and iPadOS can do it though.

Thank you, that's what I was looking for and failed to find

 

[solderdude]

One should note that the sensitivity of IEM's is usually between 110dB/V and 140dB/V.
The highly popular 7Hz Zero 2 for instance = 120dB/V.
This means that 0.5V or 1V may well be waaaayyy too high for a lot of sensitive IEMs when the goal is to limit SPL to 110dB peaks.

An IEM attenuator is the best way to go with an attenuation between 10 and 20dB that may not even be enough for some IEMs

 

[OldHvyMec]

We've had the same rule in the house for 45 years. Turn down the volume control before you turn off the stereo. The same rule applies between record flips, CDs being exchanged, or switching between any source. The only place the volume isn't turned down is the TV, but anything hooked to the TV is.

I just bought a new Fosi ZP3. It states in the owner's manual to "turn the volume knob counterclockwise several turns before turning the power on" for the first time.
I'll still turn it down before I shut down or turn on. Just a good practice, and it certainly doesn't hurt a thing.

Regards

 

[Philbo King]

Not directly related to IEMs, but I've used a stereo limiter (running at line level) for this purpose in the past. It's good to have an LED light to tell when it's limiting.

 

[StupidSquared]

Thank you all for the wonderful responses! It seems like the Apple dongle is the most idiot-proofed (easily-available!) solution, and works for my needs because I’ll only be using it on Windows/iPad (it seems that Macs already have a good line out)