Shane D
Headphoneus Supremus
Get a pair of XLR cables to connect the L/R channels from the DAC to the amp, they are cheap and readily available. That amp has a XLR-4 headphone jack so you need a a 4.4mm to XLR-4 adapter. If you bought a 4.4mm to dual XLR adapter (why?), you would then need a dual XLR to XLR-4 adapter (https://www.amazon.com/Balanced-Female-Hi-end-Silver-Adapter/dp/B010NCDVIW).
Forgot to mention that I already have an XLR headphone cable. It is plugged into my amp as I wait for my source cable (slow boat from Hong Kong).
Shane D