AC volt meter instead of Vu meter.

I like the look of old analogue VU meters however they don't actually display much of use.
A bit of mental maths and I could convert the VU to something usefull but I would rather see a display of the AC voltage of the signal at the output.

I've been pondering if I could connect an analogue AC volt meter across the outputs of an amplifier.

Something like:
https://www.aliexpress.com/item/100..._id=202311240101066275243863642730003680140_2

Is there any reason this wouldn't work?

Would it have a negative impact on the sound of the amplifier?
 
I'd expect it to not affect sound, should be high impedance. BUT, it will not be very accurate. Took a quick look and it appears to be a line voltage meter, so it is accurate for between 50-60Hz. Audio you either want peak (over full 20-20KHz) or RMS over the same range. The link looks like it will be accurate from 50-60Hz average for a continuous sine wave.
 
I find it very useful, in a way better than a regular meter, IF it can be opened and recalibrated.
Say my amplifier can put out 28 V RMS into an 8 ohm load, so 100W RMS.
If I can replace some internal scaling resistor so it shows 70% of full scale with amp just reaching clipping, personally I find that better.
To my mind, seeing "output is, say, 10-15V RMS out of possible 28V" is better than "I am 7-8 dB below clipping".
Or: "I am reaching we quarter/half of possible voltage excursion"
In fact, regular Vu meters do the same, only scale is dB and not Volts.