A quick remembrance of what the Sunflower pads were intended to be*:
(I never heard the difference the quarter mod is supposed to make, so I don't do it.)
*HD414 + extensive tape mod seemlessly covering the sides and the rear of the pad. The tape strips are overlaid perpendicularly (in a “radial” pattern) much like flower petals, which inspired the name.
This rather complex arrangement will give the HD414's 2 to 2.5 the bass benefits the original tape mod gave the bowl pads. I have a subjective impression that the details are increased just as much, but I was always alone arguing that about the original tape mod.
I chose the HD414 base pads for their transparency over all the dual-density (non-comfies) Grado pads; they are also “volume-equal”, that is to say the sound quality and signature stays the same throughout the whole volume range. I always found Grado pads to sound muffled (lacking in details and highs) on low volumes, causing me to listen to music louder than was required for enjoyment.
Leather and pads in general have always been the weakest link in any headphone. A few small companies (I forgot) have attempted to commercialize “leatherized” Grado pads before and failed: reviews were unequivocally bad. Leather is the skin of an animal, it has no inherent acoustic properties going for it. Foam on the other hand is constituted 99% of air by volume, hence it can be transparent.
Maybe a little too transparent. My conclusion was that a less permeable material is
required to transmit lowbass to the outer ear. It simply cannot travel the empty distance between the driver.
Scotch tape has a similar compliance to the mylar of the diaphragm, stiff and mechanically inert. It conduces more sound to your ear, not less (unlike leather, which might absorb part of the spectrum).
Joeq, although I am thankful you tried and reviewed my mod (“a tad too much bass”), your recent comment about it is rather shallow (focusing on things like appearance) and subjective; my own Sunflowers are just as comfortable as the HD414's and tape microphonics-free.