6.5 vs 8 vs 10 woofer

efficiency, though. You generally want a good 91db for one watt on the tweeter, preferably 92-93db efficiency.

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There are tons of choices of new compression horns which are 108-115 db efficiency. Why settle for a   dismal, poor efficient  93db, ??
Always seek high efficiency. Higher the db sens the superior the voicing of fq's This is a general rule , but more often true than not. 
In fact  now that i made the high sens discovery, its  my Golden Rule.
Thors 87db  lol 
You should go see what Seas says about their Excel drivers, In my book, none of which is true.  

I like many different kinds of woofer setups in speakers: multiple smaller drivers in the Revel Salon/Studio II and the Raidho’s, multiple larger drivers like in the Wilson’s, and right now using the 11” single Eaton driver in my Usher floorstanding speakers

 Rythmik F25s

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170 lbs of monsta bass,
I mean to ask, do you have neighbors, close by? Guess not, and your pets? Guess not. 
10 inch bass will provide MORE than enough bass in any size room. 
dual 15's ,  This is the bass The Who uses at rock concerts. 

"hate to repeat this 1m x's, but I'll say it one very last time, db sensitivity is 100% the most important tech value you ned to look at 1st in any speaker's performance."

While I agree with this sentiment 100%, there is always the exception to the rule.

15 years ago, I was in a band, and we were getting ready to do our first headlining show.  It was a small club, and we had to supply our own PA.  I advocated for us to spend fifty bucks (we were getting paid $400 for the show, so this was not a big deal) to rent a couple of mains, since one of our supporting bands had already agreed to bring a pair of their monitors for the gig.  

Our singer was stubborn, though, and was combing Ebay as hard as possible to find a different path.  One of the things I told him was that efficiency was a VERY big deal with loudspeakers, because the lower the efficiency, the more power we needed to drive them, and I didn't have unlimited amplification capabilities.  

Lo and behold, he finds a pair of mains ($100 for the pair plus $100 shipping) claiming 500w power handling and 98dB efficiency.  I told him it sounded fishy, because there would be a ceiling on max dB output, but he went ahead with the purchase.

The voice coils caught fire less than half an hour into the first band's set.  LITERALLY CAUGHT FIRE.  All we were running through them was vocals, so there's no explanation for this other than they were just cheap, shitty speakers, no matter what stats they claimed.  

Well, I combine those with a pair of SVS SB-13 Ultras to make sure there's just enough bass.

They all come with volume controls. They don't have to be turned up to 11.