Further notes as I continue to learn and discover...
Crossover as hifi buffs know very well is the way to separate sound frequencies to send to the subwoofer, mid speakers and tweeters.
I used to leave crossovers alone because I did not understand them. Now I just discovered, if I don't set them correctly, the speakers will struggle to deliver frequencies not intended for them. Which is why my system sounded atrocious previously. Yes, I am late for the party, but I am glad I finally arrived.
The player may have a crossover. The speakers also will have a crossover. The amps also may have a crossover, or high pass/low pass filter. So my question was, which crossover do we use?
For the sub, I use the crossover at the player itself. I set the low pass filter of the sub's amplifier to maximum, allowing all frequency to come through. I use the crossover at the player to decide the crossover frequency for the sub and midrange.
But for the tweeter, I struggled to find the right crossover frequency setting at the player. It just didn't sound right, too sharp.
Then it occurred to me that my tweeter and midrange speakers are from the same brand, coming as a set. Which means the crossover within the speakers are already set at optimum. So I set the crossover point at the player for the tweeter/midrange to flat, and let the speakers' crossover sort it out.
The result was much better.
Next, the player has a subsonic filter. I always wondered what it was. Turned out, it was a way to cut off the low frequency sound. Subsonic means we can't hear it. My sub has a low end limit of 25 Hz. Apart from a subsonic filter, the player also allows the slope of the cut off to be set, from Q1 to Q5, Q1 being the most gradual, and Q5 being the most steep slope. The slope is how gradual or steep the sound frequency drops off.
I always thought since it was subsonic, it made no difference because we can't hear it.
Not true. Changing the subsonic cut off with various combinations of frequency (above/below 25 Hz) and slope made an audible difference to the quality of the bass.
The learning continues...