As you can see, the typical SSB signal is very narrow but unfortunately, very "Canned" sounding as well. For more on Extended SSB Hi-fi audio, ) This is not always possible however because some gear does not provide Balanced input and/or output connectors.
Now take a look at another SSB amateur station who has done some work on his audio via processing. Not exactly like AM broadcast, but closer than the typical SSB audio without being a full 6k Hz wide. More importantly, the station was clean with excellent carrier suppression and extremely low I. You could also use audio isolation transformers between each piece of audio equipment wiring them for balanced on each side.
This would provide maximum ground-loop isolation preventing annoying hum and buzz while also providing great RFI immunity.
However, this can be costly when using premium grade transformers like the ones made by Jensen.
I'm not saying that anything less than a 3k Hz bandwidth will sound bad.
I'm only trying to point out that it will NOT sound remotely close to what AM broadcast sounds like.
Let's take a look at an AM broadcast audio spectrum vs. The broadcast AM station in white (WBBM AM in Chicago) above is producing 9.5k Hz of audio via a 19k Hz RF bandwidth. The next graph displays an SSB Hi-fi station with a transmit passband of 6k Hz.
This type of cable is known as "Starquad" and is available at many musical outlets for about 50 cents per foot.
The idea they have is this: The flatter, the better! The typical Amateur Radio SSB audio has a very emphasized midrange characteristic to it by design, especially in the 400Hz ~ 1k Hz area.
Another attribute with this kind of audio is a severely rolled off bottom end below 300Hz and a tight roll-off above 2.5k Hz.
If your transceiver cannot exceed 3k Hz on transmit, then forget it!
You will not have the necessary bandwidth to phsyco-acustically sound like AM broadcast!