301 redirects to new site

[Brenho1]

Hi,

We have two stores and are wishing to redirect all traffic, 301's etc to a new store and domain. What would be the safest way to do this as we have strong domain authority on store A which we obviously don't want to lose.

We have a csv with all the 301's ready. Will we require an external server to act as a mediary, or can this be achieved in another simpler way?

Thanks