If you look at my diagram above, you can see a 3-way speaker with crossovers at 800hz and 3,000hz. These are both High Pass and Low Pass together. The Woofer is a Low Pass blocking (rolling off) everything above 800hz. The Midrange is a Band Pass, which is comprised of a High Pass allowing everything above 800zh PLUS a Low Pass blocking everything above 3000hz. Between the two they make a Band Pass covering everything between 800hz and 3000hz. Finally, the tweeter section is a High Pass allowing everything above 3,000hz.
So -
Woofer = Low Pass (everything below 800hz)
Midrange = High Pass (everything above 800hz) AND a Low Pass (everything below 3000hz)
Tweeter = High Pass (everything above 3000hz)
Now, the only crossover in an AV Receiver is the Subwoofer Crossover, and that is typically 80hz. How does that ELECTRONIC Crossover at 80hz in any way effect the other speaker passive crossovers.
AV Receivers can be set to one of two settings - LARGE and SMALL.
Large = Full Range Front Speakers (in summary)
Small = Limited range Front Speakers, all the bass below the Subwoofer crossover is diverted to the Sub, no low bass to the front speaker.
In the case of SMALL, you have two cross overs, a LOW PASS for the Low Bass, which is diverted to the Sub. And a High Pass, which sends everything above the Subwoofer Crossover (80hz) to the Front Speakers. So, if we assume an 80hz Sub Crossover, everything above 80hz goes to the main Front Speakers.
Now, again look at the Diagram I provided. These crossovers are not brick walls, they are slopes. Speaker response doesn't end, it fades out.
But again both these AV Receiver Crossovers occur inside the amp. The speaker has no awareness that they are there. The Amp merely sends 80hz to 20khz to the front speakers, and the speaker reproduce it.
Again, because the AV Receiver Crossovers are Active Electronic Crossovers, and because they occur in the Pre-Amp section of the AV Receiver, there can be no interaction between these Active Crossovers, and the internal Passive Crossovers of the Speakers. Each has no awareness that the other is there.
For the most part, to the best I can interpret it, what your friend said is gibberish intermixed with a few twisted bit of truth.
Once again, the internal Crossovers in the AV Receiver, have no effect on the Passive Crossovers in the Speakers. Once the Amp crossovers are set, the Amp simply sends sound in the range of 80hz to 20khz to the front speakers. That Passive crossovers in the speakers simply react to that limited range of sound. There is NO interaction between the Amp and the Speaker crossovers. There are a whole lot of electronics in the Amp isolating those crossover settings from the actual speakers. So - No interaction.
Notice in the Diagram I proved, the Subwoofer is on a completely separate line from the Main Speakers, and that is because they are truly isolated from each other. Two separate outputs drive them. The Sub Pre-Amp Out drives the Subwoofer, and speaker terminals drive the Front Speakers. Nothing connects the two, except the electronics deep inside the amp. Again, there is no way they can interact.
You friend is free to believe anything he wants. He can believe the earth is flat. He can believe the Universe was literally created in 6 days. He can believe that Evolution doesn't happen. He can believe anything at all, but he has to realize that just because he believes it, doesn't make it true.
Now, perhaps there is an aspect of what he is trying to say or in what you are trying to say that I don't understand. But I doubt it. I've got a Bachelor's degree in Electronics Engineering Technology from the Physics Department. What are your friends qualifications?
Sorry.
Steve/bluewizard