Best practices for playing a lot of audio

Unity Engine
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1

Hello everyone,
I am creating a 2D Space Strategy game. Where there will be 20+ ships, firing projectiles, missiles etc. with lots of explosions etc. There are lots of sounds playing at the same time. I don’t know exactly why, but the sound doesn’t sound very good.
Currently I am using these things:

  1. Playing sounds with different volume and pitch each time
  2. Max virtual voices 128, Max real voices 15
  3. Using PlayOneShot
  4. Using AudioMixer

Here is gameplay of my game:

Please tell me best practices to make game sound better

2

Hello,
Anyone? Please help me if you can.