Best upgrade: amp or pre-amp?

@erik_squires +1 here. Luxman is a superior made product and will probably be and end game integrated Amp.

If the Focal has Beryllium drivers, then to my ears, the KRELL K-300i integrated will be an upgrade. The K-300i is a single box with optional internal DAC and ROON READY. This unit is a killer piece. I sold my recently only because I bought the KRELL Duo 175XD stereo amp in the same lineup.

The used amp listed below is what I wanted to buy but I could not make the money work, so I ended up getting the lower powered KRELL 175XD instead.

Krell DUO 300 XD | Solid state | Covina, California 91724 | Audiogon

I am not sure how this would work with your MAC preamp, but even a $2500 Benchmark LA4 would work great with that used KRELL Dou 300XD and the Focal. I know because I tried the 175XD with the LA4 preamp.

Though for the sake of simplicity and sound the K-300i is my fav integrated amp. I considered the Luxman 509x but the K-300i was more to my tastes. It sounded smoother (90 watts Class A) and had good bass power. You will not get fatigue with the KRELL. There is a recent thread on this integrated amp.

BTW - Luxman is not analytical. It is warmer than the KRELL I am recommending.

Why not stay with Mac gear? 

My initial impression is first step if preamp or amp is the amp.  And depending on your budget there are some excellent integrated amps

The second thought I have is if you can listen to different manufacturers.  All pieces are slightly different.  I've owned and love McIntosh.  I also appreciate other brands both SS and tubes. 

agree, get rid of both and buy a decent integrated. There‘s lots to choose from, some good ones have already been mentioned. If you aren‘t after big power the Leben CS600 is pretty special.