RewriteCond %{HTTP_HOST} (www.)?amplifyme\.org$ [NC]
RewriteCond %{HTTP_HOST} !^$
RewriteRule ^/(.*) http://amplifyme.net/$1 [L,R=permanent]

# If you want the site to be accessed only WITHOUT the www. , adapt and uncomment the following:
RewriteCond %{HTTP_HOST} www\.amplifyme\.net$ [NC]
RewriteCond %{HTTP_HOST} !^$
RewriteRule ^/(.*) http://amplifyme.net/$1 [L,R=permanent]