Can I use a split?

There is no risk of damage.  Whether or not sound quality is compromised depends on the output impedance of the DAC, the input impedances of the headphone amplifier and the power amplifier, and possibly also on the lengths and capacitances per unit length of the cables that are involved (especially if either or both of the cables is/are particularly long).  The likelihood of a problem is greatest if the DAC has a tube-based output stage and the two amps are solid state.

A splitter I have used with fine results is this one, made by AudioQuest:

https://www.audioadvisor.com/prodinfo.asp?number=AQM22FHRD

Regards,
-- Al
 

In some rare case (Vincent Audio?) amplifier short its input to ground while power off, an A/B switcher will solve that problem. 

Tell us the model of the dac and it's "output impedance"
And the "input impedance" of the amp (model), and headphone amp (model).
And we’ll work it output.

Cheers George

The DAC is a LAB12 DAC1 SE. I can't find its output impedance but the output level is 2.25Vrms.
I have two amplifiers, Line Magnetic LM34IA with input impedance at 100kΩ and an old Tube Technology Unisis Signature which I can't find any information about input impedance. Then the two headphone amplifiers; Feliks Audio Elise with input impedance at 100kΩ and the other is a Mjölnir KGSSHV but I can't find anything about this units impedance.
Can you come up with something using this ?