(I am using wiring clips for easy and hassle free works. The clips secured tightly I don't have to worry about poor connection)
I prefer 1 Amp per each floor. If you have 2 floors then it should be 3 Amp. 1 for the ext sound and 1 each per floor (int sound). Reason being if 1 of the int Amp failed you farm's int sound will not be totally out.
I have seen many use 1 Amp (int) for the whole building. Reason being "cost". If you visit your farm once a month and if your int Amp failed then your farm will be out of sound for 1 month. By then many birds would have left.
If you have 2 Amps or more if 1 failed you still have another 1 running. So your int sound would not be totally out. For new farms it is very important that the int sound keeps running 24/7 without stop.
Moreover having more Amps mean that each Amp handle less tweeters. This would stretch the life span of the Amp. Never push the Amp to its limit. This would shorten its life span. An Amp that could handle 150 tweeters and is being attached to 150 tweeters constantly running 24/7 would not last long compared to a similar one that only handle 80 tweeters. In this case no fan is needed because there is no over load.
Once all tweeters are fixed and attached to the Amp then the sound is ready to play. Check and tune the volume. Neither too loud nor soft.
Don't forget you need a good sound to attract Swiftlets into you new opening farm.