[TenTec] jpreamp and rf gain

[John]

Hello all !  I have a question .  I was just listening to the TT net on 14.329 and some one made reference to listening to his Orion II with the RFgain way down and then putting on the rado's preamp .  Does this procedure cancel each other out or what am I missing here ?  I thought the preamp increases the noise along with the signal ?  Thanks for setting me straight .  John kb2huk