Digitizing itself isn’t going to kill the vinyl sound; I’ve had quite good results with Meridian 808i DAC / preamp units that digitize all analog inputs input and apply DAC / filtering on output - even with very high end vinyl gear. It can be suprisingly transparent. The main thing is that if you're used to a tube preamp, you won't get its added warmth and fullness from any digital preamps (as line stages they are a bit clean and dry) - though you COULD pipe the digital preamp into an input of a tube preamp...
That said, I also had the NAD M12 digital preamp and did not like its sound, at all. The M22 amp was fine, but the M12 did not make the cut here - I think even their older M51 DAC might have been better.