Cayin headphone Amp help

Hi guys

Just one quick stupid question
I just bought a cayin desk headphone amp.

Set up is simple so far
Nuc with roon core plugged in USB to my amp
Use the Nuc as streamer.

I want to know where I should plug the headphone amp into my Mcintosh amp.
Headphones amp has two inputs
CD and Aux
One out: pre amp output

I am a little confused as I want to use headphone amp as an amp with power and pre amp stages and using Only the Mcintosh for the Dac part

I hope I am clear enough :crazy_face:

The amp is the last stage, so, your McIntosh would be the DAC, the chain should look like:

NUC > USB> McIntosh (for Dac) > analog out > Cayin Amp > headphones.

Thanks a lot!