Welcome to the forum!

I also run the A5 - but have 8 ohm woofers and 16 ohm drivers on the 803 horns.
But that is not a problem, as long as you are building your own crossover. If you are trying to use an already built crossover, it would be a problem. Look at the Hiraga crossover for the A5. Use the 8 ohm section for your horns, the 16 ohm section for the woofers. You will have to adjust the resistors on the horn, but we can help with that.

Yes, you can run these with a T-amp. I have quite a collection here and they all do well.
I am the t-amp guru, after all.