In my case the driver is a T20 - I had to replace the original driver after I damaged them. The T20 driver fit perfectly as a replacement. The tensions could have been different, but the two parts were interchangeable.
The Grundig OEM was also made for a US company and called the Concept "Constant energy headphone."
It's a T20 driver inside, and stock it came with a small bit of foam and some black mesh over the "L" vents.
Came back from a nice sunset run and popped open a Saison Dupont.
It's just a perfect refreshing dry beer for me, with a bit of fruit and spice upfront with a light bitter citrus (but not overpowering tart) finish.
It's all so well integrated and lively. Love this one.
Check out the Daptone label in general the producer behind the record has really done allot of work recreating the analog process of old and the talent on the label is solid.
With the sprung PMB100 headband, the headband could possibly cause reflections if it hung down over the back of the driver. There may have been other differences between the two, but it's been a while since there was much discussion about them here. It's great that you've found another. I don't know if we have any idea how rare they might be. They are a mass produced electronic item- there must have been thousands made.
Trying to get "moar bass" out of the PMB100 seems to require the elimination of allot of what make the headphone interesting.
Instead, I ended up accepting that there were limits to the design. I think the open aspect were unique to it and worth preserving.
Is the headband on it fixed or suspended on elastic?