[Kimball Corson]

The tape modification of the ie80 requires placing a piece of Scotch or other tape over the adjustment port aperture on each earphone ("the tape mod").

Without the tape mod, the ie80 is fatally flawed in my view. The mid-bass hump does it in, even on the best or smallest port setting. However, the tape mod saves the day and makes the i80 a decent contender. It much reduces the mid bass hump by converting the bass driver enclosure from a resonant ported reflex design to an acoustic suspension design. Warranty and longevity effects are unknown. but I do wonder why the designers did not design the port adjustment to allow for total closure so a tape mod would not be necessary. Maybe that is why Sennheiser abandoned this design when it went to the IE800. 
 
The reflex's dominant resonance is compromised by the tape mod and that is a change for the better.The aural effects are to reduce the mid bass hump and thereby to strongly clear up and not mask the lower and sub-bass, increase bass control, augment and clarify the lower and middle midrange, and make the top end more augmented and open. It protects the drivers more from humidity rises as well, when in use. The midrange is moved slightly forward, the soundstage is slightly enlarged and venue ambiance is much more noticeable. The former mid-bass hump was bleeding into the midrange and masking many details there as well as in the sub bass. It is a more intimate, articulate and still a warm sound with the mod. Ambient noise is reduced as well, that is, isolation is improved by the tape mod. 
 
I get a good seal on the ie80 with the large silicon single flange ear buds and proper insertion with ear manipulation and find the ie80 quite comfortable to use. I do not think it is quite up to the Westone W4 iterations, however. It is too colored and insufficiently neutral and level across its range, but still enjoyable to listen to, in my view. 

 

[Kimball Corson]

I bought a not-cheap, good quality 9N silver plated Ohno Cast copper stranded cable for the Sennheiser ie80. With the tape mod, it is clearly not recommended. The silver plated cable tips the whole spectral balance up and unnaturally takes the edge off instruments like the cello, brass and the voice as well. It also emasculated the bass. Frequencies below about 800 Hz are sharply and progressively attenuated and those above about 2000 Hz are mildly and progressively elevated. The very top end is improved but everything below about 200 Hz is really atrophied. The difference was quite audible, contrary to those claiming cable differences can't be heard. Break-in only smoothed things further and helped recover a tiny bit of the huge amount of bass lost by the cable with the tape mod. I did not not try the cable without the tape mod, as I did not think the prospect for improvement justified the effort to remove the tape, and then replace it if the attempt failed.

 

[Kimball Corson]

Well, as I suspected, I could not resist trying the custom cables (HiF Acoustic OCC strands with silver plating) with the Sennheiser ie80 without the tape mod. It stood no chance, I thought, of getting things correctly. Well, I am suitably chagrined. I was flatly wrong. Someone knew what they were doing with these cables. The result, with a mid-dial setting on the IEM, was similar to the tape mod but more dynamic, not surprisingly, a little more intimate and up front in the mid-range and a bit more efficient, again, not surprisingly. A lower volume setting yielded the same SPL. There is much more depth to the sound stage.  Audio processing is more conspicuous in pop music. Also, the mid-bass hump is tamed and the deep bass is more present and with more weight. The treble is a bit more resolving and more extended. Music sometimes has the raucous and occasional loud quality at times that it does in real life. The stranded and silver plated Ohno Cast Copper wire is made in Japan and then hand-crafted into the cable in Hong Kong.  

 

[Kimball Corson]

I have decided to part ways with the Sennheiser ie80. What the increased clarity of the OCC silver plated cable allowed me to pinpoint  was a noise and harmonic overhang I have heard before in 2 channel  room stereo. It derives from porting the driver chamber at the port. It is most audible on  well recorded piano. I then went pack and also heard it more muffled with the stock cables. The tape mod ameliorates it, but has its own problems, as I have pointed out. For now, I will have to stick with the Westone W4r's.