Use Sennheiser HD700 headphones with Expert 200

[CongoFather]

I was in the same situation as you and all I could find were cheap and nasty £2 cables but after experimenting with one for a while I decided to purchase a dedicated headphone amp.

Mainly because I was paranoid of blowing the headphones due to accidentally setting the wrong volume

Hi,
I just posted a message showing how to make the connection with the right cable  at Headphone Devialet Connection with Pictures
You should use an adapter cable like this product which is called as "Y Adapter" KabelDirect Y adapter

You can also search for a similar product with a female 1/4 inch female stereo jack.. Then you should configure the input near AES/EBU as pre-out.
Do not forget to uncheck "Mute applies to this output" And also, you had better limit "Max Level" setting(Max input Power) according to your headphone's technical specs. I have ben using Fostex TH900 MK2 for a along time and this value is 1,26 volt RMS for Fostex TH900 MK2.(https://www.headphonesty.com/headphone-p...alculator/)

And also be sure to set the initial startup Volume to -40, -50db using general setting on the advanced configurator page. Lastly, configure "Remote Settings" so that the 3rd button is set as "Preamplified Output" to turn it on/off using the remote control.