JBL L100 Classic to 4 or 8 ohms ?

I wonder if it's the same with the 4312G 

My 4312SE  sounds much lower and warmer.

I had a pair of JBL L100 Classics and they definitely needed a sub (or two) since they roll at about 70 hertz.  That 12" is more of a low mid driver than a real low frequency driver.

2 heavy 12`woofers need sub ? 

I supplement my JBL speakers with a single SVS PB2000 sub.  It makes a big difference, I also use a Schit Lokius 6 band EQ

One should always try the various ohm settings on your amp and decide for yourself which sounds better. It's not going to hurt the amp or the speakers.

The same thing happens to me.

How many hours does the woofer need to break?

Did you feel any change with the hours? Did you try again with 4?

I'm surprised with the woofer size and only goes to about 60hz-70hz, maybe need more hs ?

I have the JBL L100 Classic speakers connected to a McIntosh MA6600 200wpc integrated amp.  I tried both the 4 and. 8 ohm settings and to me in my room the 8 ohm setting sounds more natural.  There is no right or wrong way, whichever sounds best to you.