Put a medium sized resistor in series with the speaker and it will make no sound anywhere but the speaker's resonant frequency, where it will suddenly become quite loud. That shows just how peaky system response can become if the speaker's impedance curve is peaky and it is used with a low power amp with high output impedance, i.e. SET.

As for favorites, I'll put you down for the Proac Response 1sc. It's a mini-monitor with a 5" midwoofer and a 3/4" dome tweeter, and it does look like it must be a real nice speaker. Street price is about $2000.00. I've heard some sweet little speakers of this type, so I can understand your attraction to them. Some are fairly efficient, but most are low and medium efficiency speakers, focusing more on response linearity than dynamic range.

Most mini-monitors are like single driver speakers to me, but with a flatter response curve. Some would probably say a mini-monitor speaker like your Proac is more analytical or refined, and that a single driver speaker was more emotionally involving or words to that effect. I kinda like each type, when they're done right.

You would probably like Akhilesh's speakers that he built with Trusonic midwoofers and Vifa soft dome tweeters. Oops - Akhilesh would not approve of my using the term midwoofer. They're full-range speakers with a super-tweeter just for air. But whatever you call them, they sound a lot like a good mini-monitor. Easy load for tube amps, and a refined sound. Pretty efficient too; I don't know how much power is safe to send 'em but if they'll handle 25 watts, they would be capable of pretty loud bursts. That's pretty important when trying to play an orchestra or anything else with wide dynamic range.

Well, I've rambled long enough.

Your vote is duly noted for Proac Response 1sc, with 5" midwoofer, 3/4" tweeter and $2000.00 price tag.