From a technical perspective the question here is does the amplifier have an internal analog to digital converter which takes the analog signal in the preamp stage and converts it to digital and outputs the digital signal.
Amplifiers can have digital power stages and the common designation for this is Class D amps. However, if fed an analog signal, which is then amplified, that isn’t the same thing as as changing an analog source to a digital source.
I don’t know enough about the NAD amp to answer the first question but I have heard of amps that do place the analog signal in the digital domain. If indeed that is the case with the NAD then I think the OP has asked a fascinating question . And as other posters have indicated it will still probably sound very good. As a practical matter if he has a large collection of LPs that he wants to play. If the answer is no, and he is starting from scratch, I would stick with streaming or CDs, because it’s all going to end up as a digital waveform