So picture a resistor soldered in a 1/4 inch male-to-female adapter.
you can add resistors resulting between 32-300+ohm, no?
Could it in theory make low impedance headphones sound better on a tube amp?
EDIT: I am not sure if this belongs in DIY or in the current category, so I apologize.
Resistance adapters exist already
Yep. One of them is from Dunu.
I’m not sure they will do what you want, sticking a resistor inline with the output of the amp will drop volume obviously, and from the amps point of view it increases the load it has to drive.
But from the headphones point of view, it increases the output impedance of the amp.
The ZDT Jr’s low impedance out uses a pair of resistors/ channel I think, rather than a separate transformer tap, but it only half’s the output impedance.
Output volume being lower is not a issue for me. I’m mainly just curious as to if it changes the sound in any way
Thanks for the response!
Hmm, there seems to be a debate on how it changes the sound. Well technically all resistor should have their own colour or sound and affect it in some way, but it shouldn’t be that much to notice. I think it’s an interesting experiment. Maybe you can do it by hooking it up to a breadboard, putting the resistor and a jack to connect it to the headphone.
I was thinking about doing this:
The resistance has to be at least 300 ohms for this to make sense I believe. The DarkVoice gets LOUD.
HifiGo won’t give the option to select 200 ohm so it may be out of stock.
I’m almost hoping this experiment would make my HD600s siiiiiiiiiiiiiiiiiinnnnnnnnnnnnnnnnnggggggggggggggg!
Well keep us updated with your project 
You gotta be careful not to go so high in impedance that you have to crank your volume knob too high and expose the noise floor and grain. Im sure there’s a happy medium ground but I would suggest getting a tube preamp with some knob adjustment to it so you can dial in the sound you want.
Can’t afford one right now, but I will keep that in mind!
All I have to work with is a DarkVoice.