Yes, it has a power amp block like every amp model of the Axe. "Power Amp Modeling" can be turned off on the power amp page of the amp block (p. 12 of the Fractal Audio Blocks Guide). To my understanding this then corresponds to the pure preamp model of the JMP-1, i.e. to the real life rack preamp. And to my ears, the JMPre-1 model with "Power Amp Modeling" turned off actually sounds just like the real preamp.
