Noise can be hard to detect until you listen to another system with a lower noise floor (i.e., base level of noise). Systems with lower noise levels sound more dynamic between highs and lows and offer clearer details within the music.
For many years, I used a NAD 1600 preamplifier in my system and I enjoyed it. When I switched to a Bryston BP-25 preamp, I was amazed at the difference in detail and clarity. The NAD had a measured THD+N of 0.01%. The Bryston had a measured THD+N of 0.000339%. That measure also includes distortion, but noise can be a greater limiter than distortion in non-tube systems. I later used that same NAD in a second system and still enjoyed using it for years until I upgraded again.
If you are not hearing objectionable noise, don’t worry about it - enjoy your music. You probably won’t notice a difference until you get the itch to upgrade.