As is common there is sometimes a bit of confusion about the concepts of balanced vs. unbalanced in the headphone world. I know when I reentered after a 15 year absence it took a while to properly understand it.
Some DAC’s are able to output balanced signals via XLR outputs. Others are single ended and cannot output a true balanced signal. Their signal is strictly single ended and outputted via RCA’s. Our Naim components (sources) and preamps are only capable of outputting single ended. It will not matter if one sources a DIN>XLR out cable from Chord - the signal from the tape out of our Naim preamps will still not be balanced - it will always be single ended.
As for headphone amplifiers there are many which will accept only balanced signal input via xlr’s. Others, such as my incoming V281 and my current GSX Mini and Moon 430HA, have the ability to accept both single ended AND balanced signals on their input. They have the ability to internally convert a single ended signal feed to balanced. This will allow them to run a balanced headphone from the XLR outputs on the front panel.
Headphones - if a headphone comes with a single ended cable terminated with a 1/4" plug it will not become a balanced headphone by simply cutting off the 1/4" and reterminating with a XLR. A new cable is needed which is wired for balanced operation on both ends. Google the technical explanation however it has something to do with all 4 wires being used +,-, and return out of phase signals. It is above my pay grade 
Our V281 amplifier contains 4 internal amplifier boards. If a single ended wired 1/4" headphone cable is used the outputted signal to the headphone will be single ended - and it will only use 2 of the Violectric’s 4 internal boards. Effectively one is only using 1/2 of the V281’s capabilities. I liked the analogy the Violectric USA importer used - running the V281 with a single ended headphone is like buying an 8 cylinder muscle car and ripping out 4 of the cylinders.
So in summary as it relates to our V281 - it can be fed with any signal - balanced from certain DAC’s or single ended from our Naim preamp. The signal can be fed to the RCA or XLR inputs on the back of the V281 - it does not matter. If one has a proper balanced headphone cable terminated in 4 pin XLR the V281 will make sure that whatever signal it is fed on the back, single ended or balanced, it will be internally converted to balanced and the output to the headphone will be balanced and will utilize all 4 internal amplifier cards. The V281 will then be used to its full capability.
One can google for further information or visit headfi for the technical explanation on how balanced operation works.
I hope this information is helpful.
Best
Gregg
PS Leatherneck - several years ago I had Chord make a DIN > RCA L+R cable for me to hang off of the tape output on my 552 and connect to any headphone amplifier of my choosing. For my headphone amplifier which only accepts XLR connectors (my 3rd party Stax HA) I have a set of Cardas RCA/XLR adapters. Keep in mind these Cardas adapters DO NOT convert the signal from single ended to balanced. They simply convert RCA plugs to XLR plugs. The third party Stax amplifier has the capability, like our V281, to internally convert the single ended feed to balanced (as mentioned above)