Question Why is streaming sound quality so bad compared to a disc? Is there anyway of making it sound better?

[R2D2]

On Apple TV for example I have to turn the volume right up for it to sound ok still not great though. If everything is going streaming surely there is a way to improve the sound quality? Can you Stream DTS:X? Dolby Atmos you have to turn the volume right up. Most of the music concerts I have bought on Apple are Dolby 5.1 I would like a higher quality than that, is it possible?