High Pass a hard-to-drive speaker - Now Easy????

Good Morning,

My understanding is that the low frequency register is by far the hardest portion of the audio spectrum to drive in terms of power requirements.

If we change things around a little bit and high-pass the speakers crossed over at 80hz or so with a powered sub, how much easier do the speakers become to drive? Just a little bit? Or a lot?

In my case, I'm running Dynaudio S1.4s which need a lot of power (current especially) to sound open as opposed to congested. I'm using a Plinius SA102 which does the job quite well. If I high pass these speakers at 80hz, do the speakers become orders-of-magnitude easier to drive? Do you think I could get by with a 40WPC push-pull tube amp in this case? What about something like a Lamm 18WPC SET? An 8WPC 300B amp?

Is there an easy way to measure this? Ie - Run the speakers full range, and measure how much power the speakers are demanding, and then run them high-passed and measure how much power they need.

Reason for my inquiry - In theory, by definition, speakers that are hard drive require use of high-powered amplifiers, which by definition are always a major comprimise and less transparent than low-powered amplifiers. I'm wondering if a tough-to-drive speaker can overcome this limitation by not requesting the hardest-to-drive frequencies from the amplifier.

Thanks, and I appreciate your thoughts on this interesting subject

Todd