The Genelecs have XLR outputs, why not use those ?
The sound quality then will not be influenced and the VU-meter will still receive a good signal.

yes it will work, it is the same signal as from the ADI-2.
The Sub is filtering the frequencies for his demand.

The Genelec‘s XLR outputs are AES Digital feed-through, not even sure if they are decoupled.

The speaker signal chain isn‘t the best place for metering anyway.

I‘d buy a cheapo $10-$20 DA-converter with adjustable headphones output as meter driver and connect it to ADI-2 Pro’s SPDIF digital out.
This way a simple Germaniun diode or bridge rectifier is all that‘s needed to connect the VU.
Selecting pre FX for ADI-2’s  SPDIF out gives a volume-setting independent signal.

If you go for a standard characteristics VU-meter, there‘s no way around something like this, the audio (el-cheapo DA) can be connected directly to those:
https://www.canford.co.uk/Products/58-3 … ETER-R32AF

Works, but the TRSs share the signal path with the XLRs.
Would only make sense if ADI-2‘s DSP and volume control would not be used.

As suggested, an independent DAC with volume control and headphones output is much more flexible.
Doesn‘t need much quality, just 192 kHz sample rate capability, in case.

€13,99 this one e.g.:
https://www.amazon.de/Wandler-TEAMPD-Ko … 5&th=1

If PH 3/4 is not needed, it could serve as independent driver for the VU meters.

Usually people have the “Pro” for it’s extra outputs, then this is not true, so:

The option “Digital Out Source” always means: SPDIF/AES signal from post volume control, and shouldn’t be used for your case.

As VU-meter source the SPDIF signal needs to be pre volume / DSP.

As much as I like and prefer DAC-Mode (manual page 43), on purpose it does not offer the necessary routing flexibility.

Use AD-DA Mode (page 43) ONLY(!) for the analog (vinyl) signal path.

Store and recall the different configurations into a “Setup” each for convenient switching.

Have a look here how to switch multiple Setups with one single button:
https://forum.rme-audio.de/viewtopic.ph … 94#p193294

Additionally:
Digital masters usually are ca. 10 VU-dB louder (and 10 dB less dynamic!) than analog vinyl, and you need to leave a little analog headroom too.
So don’t expect the VU to show the same level, unless you reduce RPi4’s output level.

You can set Analog Input Trim to +6 dB for a little better level matching.
Due to ADI-2 Pro’s internal headroom of 24 dB there will be no overload / distortions, even if the digital level is (up to 6 dB) above full scale then.

Only for recording the vinyl, this setting should be used with care.