Rob80b
Headphoneus Supremus
That is exactly what I have. I had the original HD650 cables, I cut them about 1 foot up and inserted both a male and female 4 pin XLR connectors. Then if I'm listening to a SE amp, I use the adapter to get back to signal ended. Cost about $15 total.
Just to add... the fine copper strands on the Senn cables are coated so that will need to be removed, otherwise the soldering will not adhere.
I found that very fine grade emery cloth does an excellent job.
Haven’t a photo of the Senns cable but here’s a $10 job on my K701s as an example.
Still it would be nice to have Senn's OEM blanced cable (as they do look nice) for my HD700s which are on route, but they're not in the budget so it's always nice to have an inexpensive alternative to tide one over.