Incorrect, there is no noise floor in a digital system

There is, it's just ridiculously low with floating point quantization. But any quantization introduces noise, and it's right there when you convert to a fixed point file like 24 bit wav.

If it's purely digital. Not everyone makes purely digital stuff though, and you can get into trouble if you don't gain stage properly.

Edit: Actually, looking into it it seems that there IS a purely digital noise floor, it's just absolutely absurdly low, unless I'm misunderstanding something, which is totally possible.