Calculations with db are wrong

[BernhardJosef]

Describe the bug
The result of adding 2 levels is wrong
The result of subtracting 2 levels is wrong

To Reproduce
Level level1 = new Level(1.6, Level.ParseUnit("dB"));
Level level2 = new Level(0.7, Level.ParseUnit("dB"));

Level level3 = level1 - level2;
Level level4 = level1 + level2;

Expected behavior
db additions or subtractions should be executed without any transformations

Additional context
see https://sengpielaudio.com/calculator-db.htm

[angularsen]

Hi, thanks for reporting.

If you are able to, could you please create a pull request with a unit test that highlights the two errors and what the results should be? Huge bonus points if you also provide a fix for the implementation.

It will help move this along much faster, I have limited time to look into it.

[angularsen]

Relevant changes coming in #1587
Let's re-evaluate after those are merged.