MB Quart K800C. Underestimated headphones or did I just come across such an instance?

I had GMP 8.300 headphones, pretty good ones. Gave them to a friend of a musician and he appreciates them very much. I recently purchased a K800C headset, 100 ohm speakers and a microphone for online games and conversations. They were used, the rubber bumpers on the shackle were chewed off. The 3.5 mm jacks were damaged - the rings on the contacts loosened and they turned - the sound disappeared with any accidental movement of the cable or was unstable. But the sound was great. Unfortunately, there is nothing to measure. There is more bass than 650, treble and mids are the same, but the separation of instruments in the space between channels is better than 650 and Grado Alessandro MS Pro (red magnet covers). I replaced the jacks with the ones I found in the nearest store. The sound has unfortunately become a little worse - the resolution has decreased but is still very good. I plan to replace the cable with something of high quality. Perhaps they will replace the 650 and Grado. Has anyone had a similar experience? I see that GMP now also make indestructible headsets, but there are already 400 ohms, and 8.300 have disappeared from the list, which is easily visible, but if dig on the site, then can order them by writing a letter.

 

You might have to rebuild them. Sometimes those old headphones can be surprisingly good.

If you have enough experience and a safe work place fixing these headphones is doable. Hunt for a manual first. The old (user) manual must be somewhere on-line.