Noise reduction

Which band 160M?

Turn on WNB
Turn on NB

Reduce the AGCT value, engage the filters. It's not about how loud a signal is, but how much it sticks out of the noise.

Use a separate receive antenna (loop or active noise canceled verticals)

Hunt for noise sources in your house like dimmers, washing machines.

There probably is nor one-fits-all answer though :-)

73, Andreas, N6NU 

Noise is a very complex subject. The best way to reduce noise is at the source. If you can identify what's causing your noise, you can mitigate it with filters, shielding, grounding, etc. It can be a long process with no single solution.

Start in your shack - make sure your cables are top quality. Even a small coax jumper with low shield, or a poorly attached connector can let a lot of noise in. I use LMR400 at VHF and for all jumpers. RG213 for HF runs.

Grounding -- you can never have a perfect ground, but almost everyone can improve.

Power supplies - banish switching supplies (there are a few good ones, but most consumer switchers are very noisy), including wall-warts.

Look at, study, and implement KY6LA's recommendations on how to build a quiet shack. Search the Community for the link. Howard's advice is GOLD.

PS - 120 db on the panadapter? That depends on the bandwidth, so is not a good measurement. Look at the S-meter (hover over it for dBm) using 400 Hz filters and no processing or preamps. If you see 8-10 dB increase between dummy load and good antenna, you've probably done all you can.

What band are you seeing -120dBm? Noise floor is very dependent on the band and your local,environment. -120dBm is quite reasonable for 20M in a city.