thinking to buy Luxman M900u mono , what other similar amps should i look?

amp for Focal Maestro

"The magnitude lies below 4 ohms in this region, with a plunge to just 1.7 ohms at 111Hz rather than the specified minimum of 3 ohms."

"which will also demand very high currents from the amplifier. As all music has considerable energy in this region, the Focal's owner will have to use an amplifier that can genuinely deliver high powers into 2 ohms if the speaker is to be allowed to sing as it should"

"This makes the Maestro Utopia III a distinctly schizophrenic load for the partnering amplifier: very difficult for any amp to drive in the upper bass, but very amplifier-friendly in the upper midrange and treble. It is a good thing, therefore, that the Focal is very sensitive, playing very loud with only a few watts of power."

"It wasn't until the 600W Classé amplifiers took up residence in the system that I felt the Maestro Utopias were really giving me the dynamics they had promised all along."

what are my options?

thanks a lot
You might want to look into the new Parasound JC1+ mono amps 1,300 watts at 2 ohms, Stable with speaker impedance dips below 1Ω
Model Halo JC 1+ « Parasound  These new amps are really worth looking into, and about $5,000.00 less per pair than the Luxman M-900u
I may be wrong, but a Luxman M-900u power amplifier has a retail price of ~$15K, and about $10-11K on the preowned market, whereas each Parasound HC1+ mono amplifier retails at $8,495.00 (2 = $17,000). 
Parasound JC1 monoblocks or Symphonic Line Kraft. Either of them are proven to deliver both quality and quantity without sacrificing naturalness. 

Imo, a lot of todays amps which uses esoteric parts and circuitry ultimately sound just that. Esoteric but not studio natural. 
Audionet MAX monos , i red that it's on the "cold" side
not enough "meat"

saw Simaudio in few shows with Focal 
not sure what model can match?

Pass X600.8 offer a lot of power , just not sure if it's work 2 ohms or under.

other brands you can think of?

for the price (pre owned or new) Luxman M-900u look like the best option.
Mike from suncoastaudio about the M-900u mono:

"This combo clobbers the Soulution 511/520 I had in here. Not even close and it’s less than half the price. Luxman with Magico is an absolutely superb combo. This combo has amazing transients. Not sure I’ve heard better with piano. Vocals are liquid. 3D. Balanced. And musical, musical, musical. "