Yes, you could also run a from the + input to the + of each parallel group (and the same for -) but if your confused already, why bother?

Crossover                                                 Crossover              
(-)                                                          (+)
 |                                                            |
 |                                                            |
(-)speaker(+)----(-)speaker(+)----(-)speaker(+)----(-)speaker(+)  
 |                                                            |
(-)speaker(+)----(-)speaker(+)----(-)speaker(+)----(-)speaker(+)