The 2nd half of V2 is used as a cathode follower. The cathode follower is not really a gain stage, but instead is a "buffer" used to drive the tone stack with affecting the previous gain stage. The tone stack is a subtractive eq and reduces the gain. The cathode follower has a high input impedance and does not load the previous gain stage. The cathode follower provides a low impedance signal to the tone stack, otherwise the tone stack frequency response would be altered.
