regards the 125 hz roll over point.
Are you setting this in the head unit or through a filter in the sub itself ?
I would start with finding the sound curve of both drive units and tailoring it from that.
If it is in the head then it will depend on the range of the focal vs the sub + if the sub is self/alternatively powered.
If it is separate powered I would be inclined to let it have more range and let the focal drive the lower/upper mid more closely.
The Focal are a good size and power so can go deep I would imagine?
I set my sub to come in lower (100hz) simply because I used to listen to drum'n'bass so it had a lot of bass and I wanted to let it work on the low notes.
More general music seems better if you bring the Sub in higher and let the other units focus higher up.
May I ask where you got the head unit from for that price? It looks like a very nice unit.
Also if you want to give the head unit more power support it might be worth putting one of the power supply smoothing capacitors in line with the power feed, These give it a great reservoir but more transient performance for the inbuilt amp. It's not worth going up to the maxpower sizes but I did have one put on the head unit of my Volvo and it made the mid-range a lot better and more clear generally.
Oh and dynamat is lovely even if it costs a fortune!
