Comparing Receive Sensitivity Pre-amp Atten Ipo

Proper use of a preamp is quite a complex process.

First consideration is noise figure. It MUST have a lower noise figure than the receiver that follows it, or it won't actually help with weak signal reception.

It'll make the s-meter deflect more, but that's almost completely meaningless.

In HF, another consideration is external noise. If a specific antenna is receiving some specific amount of noise, and a desired signal is arriving below that noise floor, a preamp will only cause the s-meter too deflect more, but won't pull signals out of the noise.

In HF, signals are usually plenty strong enough, the problem is usually a need to reduce the noise.

Preamp, Audio Interface and A/D Converter - What's the Difference?!

Preamps don't do that.

A good application for a preamp on HF would be with a magnetic loop or beverage antenna, something that is inherently less noisy.

Active noise reduction takes a completely different set of tools.