Fredenstein U1631

This promises a whole lot more than it delivers.
First off, straight out of the box the build quality is suspect it feels like a toy. (In fact the first one I received was defective out of the box , but let's give Fredenstein the benefit of the doubt and put that down to my bad luck.)

But....this is sold as a level meter, presumably for audio professionals /studios as it uses DB25 connectors, not jacks or RCAs

Let me be clear that this is only a level meter in the loosest possible sense of the word - the release time is ridiculously slow (like more than 2 seconds) to the point where it is useless other than to indicate signal input / light show. A typical drum machine loop will not 'pump' the way your DAW meter will , this thing is too slow it will just show a continuous level.
Who designed this thing? (I have had two of these units, the release time is set this way , apparently)
Note that it has absolutely no controls, it's not +4/-10 switchable nor can the meter be set to any standard.
I could see this before I purchased it, I just took a chance and assumed it would have some kind of sensible default setting.
It doesn't. This is not professional audio equipment, although it is sold as such, don't let the DB25 connectors fool you.
If I had known, I certainly would have not purchased this.