Hi Xoc thanks for the comments. With regards to your questions:
R1 is not necessary-
Effectively thats debatable i have built xovers without it and things worked out well
C1 is quite small and could be increased to make sure that the passband is not effected-
I will check it again but simulation shows its ok. The final sub will aim at 30Hz -3dB
RF input filter looks sensible.

Cool
The buffer into the gain control seems OK. I prefer a small value resistor (100R) in the feedback loop of a buffering op amp, apparently this helps the op amp recover from with any spikes which cause clipping.
I was not aware of that it won't hurt adding it
C11 is probably not needed-Its to avoid any crackles in the sound
Are R14 and R19 necessary? Re-arrange the filter stages so that one of the high pass filters is last in the filter chain, and this will block the majority of any accumilative DC offset-
Great Suggestion will do that
I don,t really understand the circuit at IC X7? -
Its a phase inverter i forgot to add the switch which connects the non-inverting input to ground
What does R23 do?-Basically ensure that the LR transform is fed properly.
Is the buffer at IC X9 necessary? Would IC X8 not drive the output? If the buffer IC X9 is desirable, then maybe the inverting output buffer X10 should be connected to the output of X8 to avoid going through an extra stage?
Well actualkly i don't mind as otherwise it would leave one opamp side unused so better use it.
R32, R37 and R38 are not needed.
R32 is essential here i would leave it as for R37 and R38 effectively i ave just left it there for simlation
There is no decoupling shown on the op amp voltage rails. For optimum performance I would use some pairs of 100uf throughout the circuit depending on the physical layout, and local 0.1uF or 0.47uF decoupling caps as well.Where one op-amp drives into the virtual earth of the next stage it is a good idea to add a decoupling capacitor right across both the voltage rails.
For usre i will use decoupling caps 0.1 uf at each opamp supply rail plus am planning on putting the reulators and smoothing caps on same board
I will re-adjust the schematics and post it again.