JBL L100 Classic to 4 or 8 ohms ?

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. 

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 ?

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.

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