Magnepan say the mid/high and bass panel consume about the same power, plus I’m using dual subs. So, roughly equal amps should play well.
Magnepan crosses over fairly low in frequency and uses (usually, lots of variance) low-order crossovers that provide a lot of overlap among panels. That, plus lack of extended (very deep) bass, means bass and mid panels require roughly the same power.
I guess it’s free to try. So I’ll give it a go.
Perceptual bias means you will likely hear improvement even when there is none really there. That's OK, but just know the improvement you hear may not be real. There's nothing wrong with bi-amping, and you already have the amps, so nothing lost by trying.
I still don’t understand how it won’t play significantly louder but electronics isn’t a forte.
There are multiple parts to the answer. The people above, and linked article, goes into it in some detail. Any real improvement happens at the very loudest levels so unless you are regularly clipping your amplifiers you won't hear any improvement (in a blind test). Note that, while bi-amping does not significantly increase available power, even if it did actually double the power that is only a 3 dB increase in SPL, a very modest increase that is just noticeable to most people when adjusting the volume. Doubling the perceived loudness requires 10 dB, and thus ten times the power, assuming your speakers can handle that much.
I always think of electricity as water, there’s pressure and flow. It seems to me that it should be louder because theres more capacity. If I were trying to water a lawn with two sprinklers I could double the area of lawn I could water, I could fill a pot twice as fast.
That analogy is used a lot but has its limitations. This is a very hand-waving explanation that might (or might not) help.
For bi-amping, using two similar amplifiers, the analogy only works if you are using all the available water from one hose and then add another. You cannot exceed the available water from your tap, and ultimately from the provider (city water, well pump, whatever). What happens to the shower flow if you run all the other taps and flush all the toilets in the house? Yeah, the flow drops, because the source can only provide so much. It works for lawn sprinklers because they limit (reduce) the flow rate by using a smaller orifice, so adding another sprinkler takes advantage of the margin (additional flow rate and pressure) in the house's water supply. If you had a open fire hose running out in the yard, there probably would not be enough flow for the other tap.
The amplifiers similarly limit power to the maximum they can provide, at least until they are limited by what the incoming electrical service can provide. Ignoring the service limit, consider a 100 W amplifier feeding a woofer and a tweeter. The maximum either driver can ever see is 100 W from the single amp. If you bi-amp with two 100-W amplifiers, then again the most either woofer or tweeter can "see" is 100 W. Nothing ever sees 200 W. Any gains are due to limiting the frequencies into the amps, which requires a crossover before the amps to split the frequency bands, and subsequent reduction in signal level to each amp. Look up "equal loudness curves" and you will see that by far the most energy is used in the bass, so the extra power for the tweeter is not much of the total power. The difference can be 20 or 30 dB depending upon frequency, a power factor of 100 to 1000 times. Even if just 10 dB, a factor of ten, that means the bass is using about 90% of the amplifier's power, so again adding an amp is not helping much.
It’s too bad I can’t just test drive some giant amp.
Perhaps, but again you would need a really giant amp to make a significant increase in loudness. Ten to 100 times the power of what you have now.
As an aside, I had Magnepans for many years (since ~1979), and in a number of configurations (single, horizontal or vertical bi-amped, rarely tri-amped). I found bi-amping with a line-level crossover required more work to set up and offered little benefit. For the last 10+ years I ran my MG-IIIa's with a single larger (300~500 W) amplifier, and switched back to bi-amping a couple of times using an active crossover, but the single large amp sounded as good, and as loud, and was much less effort to implement. Ultimately I stuck with a single large amplifier and quit second-guessing myself. I did use a DH-200 for a while, among others (tube and SS), but at the end was using an Emotiva XPA-2 (original) claiming 500 W/ch into 4 ohms. Not the best amp in the world but sounded OK to me.
HTH - Don
