Petr,
I am not 100% clear what you asked for.
Do you ask for:
1. An amplifier model that can be used together with TPA3111? or
2. TPA3111 pspice model?
If this is the second one, we already have have TPA3111 pspice model located on
TPA3111 product folder: http://www.ti.com/product/tpa3111d1
You can open the .lib file contained within TPA3111D1 TINA-TI Spice Model (Rev. A)
and you can try to import it into Altium Designer. If it gives you error, let us know, but usually
it should work with no problem.
Herman