What is a good sounding tube amp for the stage?

Just to cover another base. Call E Guitars in San Rafael, California. This store is almost a museum and their knowledge of vintage equipment has got to be right up there.

If you play Guitar this is a must see store.

What will the amp be reproducing?

What size room?

How many people?

What is the overall setup?

What sort of speakers will the amp be driving?

We want to produce pop concerts in theatres with 2500 seats. I am trying to do it with quality sound - liquid and transparent.

Can it be done on pro audio?

I am considering EAW La speakers - will this do it, or is there better?

Is there a digital amp that will do it, or should I go with tube preamp, and transistor power amp?

How many sets of speakers do I need?

Thanks in advance...