Path from Phone to Headphone Amp

[cscottrun4it]

Let's see if I clearly understand the path from my phone to a headphone amp with RCAs in:

USB C - > 3.55 mm female dongle - > 3.5 mm male to RCA adapter - > headphone amp​

Really? How do you figure out the impedence on this mess? I know the impedence on the amp, but all those adapters? Am I nuts here? Is there another option?

 

[cpt_paranoia]

The headphone amp output is the only thing that matters as far as the headphone impedance is concerned; the amp buffers (isolates) everything prior to the amp input.