Do we really need anything more than 8" woofer and 1" tweeter for medium size room?

Phusis, that's the task for a driver designer to find the best compromise possible. 
Orpheus10, yes coherence is much more important than frequency extention. That's one of the reasons, perhaps the most important one, of why one set-up sounds right even if not at all perfect and another one wrong even if it could sound impressive for the first minute.

8" is too small. Show me a speaker with an 8" driver that goes down to 20hz with less than 5% distortion? Not room gained down to 20hz but real output. 

@james633

Show me music that has that much content below 40 Hz. Show me an affordable speaker that goes down to 20 Hz with measured low distortion. Show me a modest living room that doesn’t have significant room modes below 80 Hz.

So, I think for a lot of people, properly set up, 6" to 8" is a sweet spot.

Is it perfect? No, but, properly set up, it’s magical. For specmanship not so much, but spec’s don’t listen to music.

Getting that last octave right is a challenge financially, aesthetically and effort.

I have a Hsu 15" 1,500 watt subwoofer sitting right next to my main speakers with 6.5" woofers right now. It's not even going to be plugged in until I have guests over for movies. Why? Huge pain in the butt to get right. :) I've experimented and carefully calibrated it for music in the past.  It was honestly a "Meh" experience.

Depends of course on what part of music you want to experience. If that last octave is where you live and breathe of course this would be unnaceptable. 

By the way, these speakers have convincing output to 30 Hz in room and can play much more loudly than I care to listen.

Best,


Erik

Here by the way is a really good 2 way speaker kit with a 10" woofer, would run you around $1k to build it yourself.

https://www.madisoundspeakerstore.com/2-way-speaker-kits/seas-a26-10-2-way-kit-pair-based-on-the-cla...

I have no financial interest in whether anyone here buys them or not, just thought I'd offer it up to any who might be reading. One of the big advantages to building this kit is you can set the treble balance exactly how you like it. :) 

Best,


Erik

X2 on show me the music .
What constitutes affordable? I will say it till im blue in the face there are numerous spkrs with smaller drivers that are beyond killer . I have had probly 40 pairs of spkr in my yrs . Again my cerwin vegas in the 80 would peel your face off audiophlie nada . Kef,infinity,polk,logans,ads,ar, maggies,proac etc. etc rel velodyne hrs sunfire 8-15" subs etc . Jazz progressive rock and Rock mostly,guitarist arist for 30 yrs . I have adagios in my audio room 2 6.5" underhung transmission line floor standers love them . Sunfire hrs12" 1000w sealed spiked sub . Rarely turn it on treated room . Earth shattering bass no, bass hell yes. Room treatment and eguipment play a huge roll . 500-700 bks does not make a world class sub lets get what the goal and budget are first . A serious 12" driver alone is 500bks if you want to rattle the walls go big if you want accurate ya better be ready to drop big bks if your talking audiophile quality. Jl is the mark imo for the bks around 2k for a 12" . I would rather have two 10" jl audios then dam near any single any size sub until you start talking serious bks 5k up each .classical music generally goes much deep then rock as most of you already know
jmho