Choose an amp on the basis of its sound quality, not its connection type, except perhaps if you need to locate the amp a long way from the Atom in which case a balanced connection can help.
Ultimately you have to listen and decide for yourself; there won’t be a definitive answer.
Obviously a Naim amp should be considered. But it’s not compulsory.
What does “adequately” mean? I gave you 3 perfectly suitable amp suggestions in the first response to your question. In which way are none of those 3 amps “adequate”?
What amp you choose has very little to do with the Atom HE (e.g. connection if you insist on XLR) and everything to do with your speakers and room. And budget. The HE is not really a limiting factor.