Source is USD in the US.
In Thailand I have both USD and THB accounts so I can transfer either with or without currency conversion. Currently in Ireland I only have EUR accounts. The exchange rate with the bank in Thailand into THB isn't quite as good as an online broker but it's still pretty good, the spread is under 1%, so 0.5% off mid market.
Anyway I'm happy with my options to transfer to Thailand, the question is about transferring to Ireland.
Key is that they accept domestic ACH transfers into an account with my name on it, which Bangkok Bank does. I don't believe the likes of Currency Fair have this option. In fact from a quick Google I think they stopped serving US customers at all.
If there are any other services that will do this, let me know, and I believe some may accept US direct bank transfers but the key is they would have to accept an ACH transfer to a bank account with my name on it- Bangkok Bank gives me a unique account number in New York for this. I can't add "advice" to the transfer as to who it should be credited to if going to a shared account.