611s

I would go with a Mac 300 wpc amp. A pair of 611 monoblocks is overkill for those speakers

The first watt is all that matters.  If the first watt sucks, it the next 599 don't matter.

My speakers are "rated" at 800 wpc.  that is the max you can put into them without blowing something.  That would be good if I was using them for a PA system at a football stadium.   I'm driving them with a 2 wpc SET.

My speakers are more sensitive than yours so you'll need more wattage.  At 91 dB you're likely limited to SS amps but some will argue that.

Buy the best quality amp you can afford.  You'll need 100 watts unless you are planning to damage your ears and exit the hobby as quickly as you entered it.

Most of the time you'll be listening to 1 watt or less.

So I'd say don't buy an amp that spent money to make 600 watts, but one that got the first watt right.

Jerry

Thank you guys . Great info and a huge help!  much appreciated!

@ranchman66 

The McIntosh MC 611s will drive anything. I have a pair driving the challenging load that a KEF Ref1 Meta presents.

Also, the Focals can be a little bright sounding, and the Macs will warm them up a bit and make them sing. If you like bass/mid-bass, you can not do finer than Macs. However, if you enjoy an analytical presentation, you will need to look elsewhere. 

Lastly, I have always applied the tenets of what "gear heads" have discovered. There is no replacement for displacement! I owned a very good SET amp and now own some "big boys." I'm never going back. 

The more wattage the better. Most amps perform their best at around 15-25% capacity. This is where the distortion is lowest and dynamic range is best. Lots of other factors to consider also, such as current, amp class, design etc. but if you can imagine, 4 cylinders have to work a lot harder than 8 or 12.  A good rule of thumb is to have an amp that can put out twice what your speakers can handle,but do watch out for "deceitful specs.  For example, an amp that claims 100 watts at 2 ohms is not the same as an amp that claims 100 watts at 8 ohms.  The one claiming 100 watts at 2 ohms is much less powerful.