Head-Direct recently launched a sibling to the RE0 earphones we reviewed a while ago. Dubbed RE-ZERO the resemblance to its predecessor's name is clear, however, the two share very few things. Just about the only thing that ties the two together is the shape and material for the housing, everything else is different. Surprisingly enough the RE-ZEROs feature balanced termination in the shape of a 3.5 mm / 1/8" TRRS (Tip - ring - ring - sleeve) connector instead of the usual TRS. Normally TRRS equipped in-ears feature a spare channel for a microphone, but the ZEROs are different in that respect. The additional channel means that both channels have their own ground making them capable of fully balanced operation.Head-Direct says that they have balanced headphone amplifiers (yes in plural) in the works ready for launch within two months. Which means they will probably do a balanced portable amplifier along with a desk version (pure speculation on our behalf).Currently only one portable amplifier allows for balanced operation and that is the outrageously priced Ray Samuels Audio Protector, which features a balanced connector not made for repeated insertion (plug manufacturer has confirmed this).The adoption of 3.5 mm TRRS for this use is very neat. Not only is it a time proven design it is also easy to adapt for DIYers and amplifier makers.