Does it result in a loss in quality for my audio file, if I record really silent and have to apply strong gain (+30dB) in my DAW, instead of just recording the signal a little louder by increasing the gain in my mic-preamp?
Does it make a difference?
Even assuming that you have perfect analog and digital hardware that produces no noise of its own (an obviously unrealistic assumption), recording at silent levels and amplifying digitally means that the result will have a lot of "quantization noise" by using too few different digital values for representing different analog values. Any difference not captured by your A/D-converter is lost for future processing.
In practice, the resulting amount of noise will be significantly more than just digitization noise since audio systems where quantization noise is the main noise source would be designed with a rather strange balance between analog circuitry quality and A/D resolution.
It may make a difference.
Your sound card (and whatever else comes after your pre-amp) will inevitably add a certain level of noise to the signal itself, as will the pre-amp itself.
If your pre-amp provides a very low level of noise, then increasing the gain will result in a better signal to noise ratio later on in the chain if there is noise being added (By any other amplifiers or sound cards), as the amplified signal will dwarf the added noise.
