Are VU-meters really necessary?! If you can't hera how loud you play, why do you need a visual indication??
Well, VU-meters are cool if they look cool. Below are a few such meters that can give an amplifier a groovy look and you can tell your friends - Look, how loud we're playing!

The kind of display found on plastic combo-systems from Poyineer, Matahari or Haifai, with blue waterfalls are NOT GROOVY NOR COOL.
The coolest is the VU-meter built on a Russian plasmatube - IN13 (IN9). There's a French guy selling kits and I have two of those. The THAT IC may be a bit hard to buy, at least it took me some effort to lay my hands on some of them. The 2252 (or modern replacement) is a RMS/DC-converter, and sorts of guarantees a nice processsing of the signal.

Another tube device is the "magic eyes", like EM84 (se link to various tubes below). It is used the same way. Kits for these simple VU-meters are obtainable cheaply on eBay or AliExpress.

Very popular were the ICs LM3914/3915 constructing simple VU-meters with a number of LEDs. The 3914 is linear and the 3915 is logarithmic, making it more useful representing sound levels.
Now I run into VU-meters with LEDs and propably some kind of circuitry like the LM3914/15. There are links to sellers on eBay and AliExpress.












French IN-13 VU-meter

VU-meter on eBay

eBay (no tube)

THAT 2252 data

IN-13 data

Driving IN-9

32 LED VU-meter (AliX)

32-LED VU-meter (eBay)

EM84 as VU-meter

Replacing EM34 by 6E5S

Magic eyes

Precis dB monitoring