To clarify the question: As far as I understand, a ADC (Analogue to Digital Convertor) will sample and therefore quantize an analogue signal. Does a ADC therefore output a Pulse Amplitude Modulation (PAM) signal? And if not, why not?
If you look at Pulse Amplitude Modulation, on Wikipedia, you see that PAM "..is a form of signal modulation where the message is encoded in the amplitude of a series of signal pulses". Therefore, the mere sampling of an analogue signal results in PAM. The article goes on to say "Demodulation is performed by detecting the amplitude level of the carrier at every single period." However, when an analogue signal is sampled, the information is encoded. No actual need for modulating a carrier. It seems.
P.S. The question may appear rather odd, but I'm coming from the world of AM and SSB amateur radio, where modulation conjures a certain image of what modulation amounts to.