That is pretty interesting. Although the philosophy for receiver performance has changed over the years. I do well remember the famous signal to noise spec. You hardly see it anymore. Now days the term is "dynamic range". It has been found that the single most important circuit or stage of a receiver is the receiver's first mixer. This is where you want to take care. After that, just make everything clean clean clean and if your first mixer is working right. You got a receiver!
I will attempt to sum up briefly what dynamic rage refers to. Though the mixer is used in conjunction with the local oscillator to select a particular frequency, what is actually happening is the entire band of frequency is in the mixer all at once. So when we speak "signal/noise" it may be the opposite result you are really trying to achieve. Because attempt to over amplify a signal, you are in effect amplifying the entire band of frequencies. That means that Joe's alligator station down the street will be amplified too. You do not want that because Joe's alligator station will over drive the mixer causing it to go into an over driven distortion mode where everything in the band inside the mixer will be modulated by his station. So now we have the modulation of the selected signal modulated by our friend Joe. This is the infamous spec IMD (intermodulation distortion). All ports in that first mixer are important. But you can now see that S/N can be very undesirable at times. Also a good post mixer amp will have allot of effect. You do not want any reflected or standing wave products coming back into the mixer for reprocessing.