Adding headphone amp with no fixed out (preamp)

A lot of head amps sport a Through out switch which cuts the head amp and you can listen to the other thing you want to listen to.

Would help a lot if you’d just tell us what preamp you bought so we can see the available connections.  Usually hooking up a headphone amp isn’t a problem, especially if the manufacturer makes both preamps and headphone amps. 

@soix 

Denafrips Athena. Was pondering an Artemis (though may not want to spend that much).