If you can integrate two sets of speakers there is a plus side....music can come across much more dynamic with less strain at louder volumes. The issues is, "if you can integrate them"! Problems arise with phase cancelation, which causes colorations and issues with effecting the soundstage width and depth. However, when done well, it can be of great benefit.
There are many multi-driver/ cabinet systems and running two main pairs can be seen as sort of a quasi-multi cabinet system.
However, that being said you might be better served to run a pair of subs with your speakers, which will increase your frequency response and soundstage, which subs tend to do.
A 40 year old amp could be perfect, if it has be gone over by a tech. and out of spec components replaced. It might give you the sound you want and be the right right eye candy, too.
I'm not that oriented with what works with Focal speakers but, so other should chime in with their recommendations.
There are many multi-driver/ cabinet systems and running two main pairs can be seen as sort of a quasi-multi cabinet system.
However, that being said you might be better served to run a pair of subs with your speakers, which will increase your frequency response and soundstage, which subs tend to do.
A 40 year old amp could be perfect, if it has be gone over by a tech. and out of spec components replaced. It might give you the sound you want and be the right right eye candy, too.
I'm not that oriented with what works with Focal speakers but, so other should chime in with their recommendations.