Clearly you mean 'assembled' in the USA. There is no new tube amp that does not contain some amount of 'foreign' content. You may be able to find a vintage amp with a lost less foreign content but in bringing it up to spec you will need to use foreign parts.
Finally, not to get 'political', there is legislation moving in Congress that will require all goods sold in the USA to clearly show the percentage of non USA content. I can't wait. It will be another way to 'rate' audio goods.
Finally, not to get 'political', there is legislation moving in Congress that will require all goods sold in the USA to clearly show the percentage of non USA content. I can't wait. It will be another way to 'rate' audio goods.