Amp & headphone amp plugged in simultaneously?

Hello gentlemen, I couldn't don't a solution so I'm dilemma.  From my preamp/dac (amr-dp777 I tried XLR into my main amp (plinius) and then RCAs into my headphone amp (topping a90) and vice versa.  I also tried rca splitters at the preamp.  When any of these happen my headphone amp gain is substantially reduced.  I take it I'm reducing the impedance even though the plinius is off?

What I'm trying to to is avoid having to unplug the plinius everytime I want to use my headphones, surely there is a solution short of buying a dac/preamp what also serves as a headphone amp?

Thank you for your time.

Weird this happens with high input impedance amps, unless the XLR output is getting grounded or something like that.


Sure you don't just need lower impedance cans?
I run balanced from DAC to pre and single end from DAC to tube headphone amp.
9:00 balanced and 10:00 balanced to Quad cans LOUD
I don't know what I need, I have LCD2s which work find as soon as the plinius is out of the equation.
Just use the Plinius as the headphone amp.
Buy some speaker adapters here, tell tell to make it for your amps binding post & plug them in