Headphone-focused tabletop streaming kit?

[EvShrug]

It can also be used balanced with just a change of cable - or even by just fitting an appropriate plug on the supplied cable.

Be careful…
I believe the HD 560S cable is internally wired as balanced until the plug, so you could possibly cut off the plug and DIY solder on a balanced plug, however do not put a balanced adapter on the end of a single-ended plug, that would cause a short and could destroy your amp.

 

[Gray]

Be careful…
I believe the HD 560S cable is internally wired as balanced until the plug

It is
A fine soldering iron was essential to fit this:

4.4mm 5 Poles Male Full Balanced Headphone Plug For Sony NW-WM1Z NW-WM1A Player | eBay

100% brand new and high quality<br><br>Features:<br>Suitsble for Sony NW-WM1Z NW-WM1A AMP Player.<br>Type: 4.4mm 5 Pole Headphone Plug Adapter<br>Material: Copper & plastic<br>Diameter of Tail-Hole: 6mm<br>Plug Diameter: 4.4mm<br>Length: 45mm/1.77inch<br>Color: Gold<br>Quantity: 1 Pc<br>Note...

www.ebay.co.uk

Then fitted (an appropriately wired) one of these to the cut off 6.35mm jack:

1PCS 4.4mm 5Pole Headphone Plug Adapter For Sony NW-WM1Z Female Converter Black | eBay

Find many great new & used options and get the best deals for 1PCS 4.4mm 5Pole Headphone Plug Adapter For Sony NW-WM1Z Female Converter Black at the best online prices at eBay! Free delivery for many products.

www.ebay.co.uk

To effectively end up with a choice of 3 metre balanced or SE cable.
They certainly didn't need to use 4-core cable - but I'm glad they did.

 

[EvShrug]

It is
A fine soldering iron was essential to fit this:

4.4mm 5 Poles Male Full Balanced Headphone Plug For Sony NW-WM1Z NW-WM1A Player | eBay

100% brand new and high quality<br><br>Features:<br>Suitsble for Sony NW-WM1Z NW-WM1A AMP Player.<br>Type: 4.4mm 5 Pole Headphone Plug Adapter<br>Material: Copper & plastic<br>Diameter of Tail-Hole: 6mm<br>Plug Diameter: 4.4mm<br>Length: 45mm/1.77inch<br>Color: Gold<br>Quantity: 1 Pc<br>Note...

www.ebay.co.uk

Then fitted (an appropriately wired) one of these to the cut off 6.35mm jack:

1PCS 4.4mm 5Pole Headphone Plug Adapter For Sony NW-WM1Z Female Converter Black | eBay

Find many great new & used options and get the best deals for 1PCS 4.4mm 5Pole Headphone Plug Adapter For Sony NW-WM1Z Female Converter Black at the best online prices at eBay! Free delivery for many products.

www.ebay.co.uk

To effectively end up with a choice of 3 metre balanced or SE cable.
They certainly didn't need to use 4-core cable - but I'm glad they did.

Nice job!
If you think about it, and think of each driver as an electrical circuit… each driver will have a positive and negative terminal. So, it starts off wired as balanced, and to keep the option at all the headphone Jack and thus one end of the headphone cable must be balanced as well. Wire is cheap, so they just solder together the (I believe two + terminations?) to the “ground” termination in a single ended plug.

Re-using the remaining length as a SE extension cord is a great idea! Waste not…

I don’t own a soldering iron myself (yet?), because I am lame 😂

 

[Gray]

Wire is cheap, so they just solder together the (I believe two + terminations?) to the “ground” termination in a single ended plug.

....the two negatives to ground 👍
Before I get reprimanded for taking the thread off the actual question:
You've already pointed out the risks of fitting your own connectors.
I must also add that supplied cables (including Sennheisers) often contain Litz wires, which is challenging to work with (to say the least).
So anyone considering modification should think carefully before hacking off plugs 🤔😱

 

[hearpary]

You have a solid budget, you can almost buy a car for that amount.

 

[skinnypuppy71]

Njc audio reference headphone amplifier
Njc audio reference dac
Bluesound node 2i
Beyerdynamic dt1990 Pro or a nice planner magnetic from hifi man.
Job done and you'll be safe in the knowledge that your helping out the UK hifi cottage industry.lol.
Sennheiser hd660s are not that great btw bored the life out of me and I traded them in.