There was a day when I can conveniently refer to the RE-0 IEM as the “r-e-zero”. Then Hifiman released the RE-ZERO, and since then I’ve been having problems differentiating between the two when I’m in the middle of a phone conversation. Do I say “r-e-zero” for the RE-ZERO and “r-e-o” for the RE-0? I guess the chinese doesn’t see this as a problem as they can refer to the RE-0 as “r-e-ling”.
Build wise, the RE-ZERO is mostly similar to the RE-0 with a few minor differences. Instead of the black paint, the housing is now painted dark grey. The grey finishing looks better than the black RE-0, and the grey RE-ZERO also has a better finishing quality than the RE-0. I noticed that sometimes the tips get stuck inside my ear while trying to pull out the RE-ZERO from my ears, and that never happened with the RE-0. Upon closer inspection, the notch that holds the rubber tips is shallower on the RE-ZERO, hence rubber tips don’t hold as well as the RE-0.
The RE-ZERO also ships with 3.5mm TRRS jack where other IEMs ship with mostly a regular 3.5mm TRS jack. The TRRS have two ring sections, allowing four different path for connection. Normally you see TRRS jacks with IEMs that have a built in microphone. On the RE-ZERO, the extra ring connection is used to provide independent ground path for the left and right channel. In order to use the RE-ZERO with a standard 3.5mm out on Ipods an amplifiers, you need to use the supplied TRRS to TRS adaptor, which come in two different shapes. Of course this is a real inconvenience for practical day to day use. But one day, when Hifiman released their portable balanced amplifier, the TRRS jack will allow a direct connection for a balanced driven IEM.