What I recently learned, was that there is another reason to have an active bass/ subs in your speakers, or power them separately either internally or externally. It’s more than just the mere need for power.
Reason is that the impedance differences between tweeters and mids vs. woofers is significant, especially in larger speakers. Therefore, the amp has to fulfill very different loads in parallel, when powering the top and low end at the same time. This will always yield a suboptimal result.
In a conclusion, bi-amping through either a partly powered speaker or separate power amps for the tweeters/ mids and woofers will always yield better results.
Whether the bi-amping is achieved through a more or less powerful amp, is another question. But I would look at separate subs and compare. These are typically very highly powered compared to regular amps (500-3000W), as amplifying the bass yields a lower impedance. Depending on how much power you have on tap results just in more or less headroom in the bass.
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