I tried that method
If this does allow more bass output, wouldn't cutting the current ring do similar?
When experimenting with the material, I cut the pieces to match the stock foam rings. To my surprise, the bass frequencies were improved however the treble levels were down significantly. Specialized equipment to measure this are not as good as using your own ears to listen to sound signature. That is where I started fiddling with the center ring diameter and cut-out. It was a hit and miss and surprisingly, the hit was a pleasing result. I manage to reinforce many of the subtle nuiances in a music track such as Alan Hovhaness City of Light.
The only downside I can hear with my modification is a deadening factor applied. The original foam rings basically introduced clarity and rather dry sonic sound-stage quality. With this dry quality, introduces a bit of harshness that can actually destroy the overall listening experience in the form of fatigue. My ears are rather sensitive to a very broad range (tested by a doctor from 10hz to 26KHz) and the K701 really makes my ears hurt before the modification that is. After the modification and careful experimentation, I have finally reach a point that the only way to gain significant improvement with these headphones is by changing the cable. I am very fond with what Moon Audio has to offer, however the only reason I haven't taken the plunge is the flexibility factor. The stock cable is much more flexible than that of the upgraded cable.
I will post more results as time and sound progress.
Until then, have a great week.
thanks for keeping this thread open.