While <1db louder 'can not be heard', my experiments (at PBS) show that even 0.5db louder sounds 'slightly better' not 'louder'.
Classical has great dynamic range. Perhaps >50db. Getting that through a 60db transmitter and back through a 70db receiver and fighting background noise due to a week signal causes my phone to ring. (back when I worked broadcast) "I can't hear the quite parts." My goal at the classical station was to set on the peaks and boost the quite parts to a point where no one complained about compression and few complained about the quite parts. We told every one there was no audio compression!
Car radio music: The background noise in a car is about 30db down. Non classical audio (radio or CD or tape) should not have anything quite than -30db. I limit and usually compress hard for 'car audio'.
My last CD, the band wanted 'no audio compression'. Against my better judgement I set the loudest part of each song to 100% on the CD. You had to turn the volume all the way up to hear. Switching back to radio or another CD caused a very loud jump in volume. The noise level was real bad. I only made 10 copies. The band rejected them.
Next I, by hand, edited the loud parts and made new CDs that were 10db louder. (no compression) That was better but still rejected.
Next I used the limiter with no compression and got another 10db louder. That was better but still rejected.
At the end we went to press with limiting and less than usual compression plus I expanded the noise down.
...I set on the peaks by 6 to 10db.
...Reduced the dynamic range a little.
...If there was no signal I reduced the gain by 20db to hide noise.
I charged them for "mastering" the CD "with no audio processing". LOL
They are happy.
I used a three band compressor/limiter/expander. Each band (high/center/low) gets processed separately then combined and processed again. By separating the bands, symbol crashes and base drum do not effect the mid band vocals.
I know all this adds distortion. My only goal is to have happy listeners. The loud should not break the speakers (or your ears). The quite needs to be above the noise level by a good amount. The how I do that should be undetectable.
Most of us listen to hard limited, heavy compressed music and speech to the point where uncompressed music does not sound right. (TV, Radio, CD, tape, vinal..... all pressed even if we say it is not) You can get classic with light limiting. With out limiting the loud parts just distorts.