An earphone comprising: an acoustic driver; an acoustic driver module including a rear chamber and a front chamber defined by a first shell and a second shell, respectively, on either side of the acoustic driver, the rear chamber being sealed around a back side of the acoustic driver by the first shell, wherein a nozzle extends from the front chamber into the entrance of the ear canal; and an in-ear portion comprising: a body having an upper portion shaped to make contact with the tragus and anti-tragus, a surface that rests against the concha of a user's ear when worn by the user, and a lower portion shaped to enter the ear canal, the lower portion being not relied upon to provide retention of the earphone in the ear, which allows it to seal to the ear canal with minimal pressure, wherein a first void in the upper portion receives the acoustic driver module, the nozzle extending into a second void of the lower portion, the lower portion forming an outlet section, the outlet section providing a passageway for conducting acoustic energy from the acoustic driver to the user's ear canal, and a positioning and retaining structure having an inner leg and an outer leg, wherein the inner leg and the outer leg are attached at an attachment end to the body and attached at a joined end to each other, wherein with the in-ear portion in its intended position, the outer leg is urged against the anti-helix at the rear of the concha and the joined end is under the anti-helix; wherein the nozzle fits inside the outlet section and has a rigidity, wherein an outside dimension of the nozzle is smaller than the corresponding inside dimension of the outlet section, wherein the difference in dimensions provides a space between the nozzle and the outlet section of the body; the space resulting in an ability of the lower portion to conform to the ear canal, and the rigidity resulting in an ability of the outlet section to conform to the ear canal, without substantially changing the shape or volume of the passageway. an acoustic driver; an acoustic driver module including a rear chamber and a front chamber defined by a first shell and a second shell, respectively, on either side of the acoustic driver, the rear chamber being sealed around a back side of the acoustic driver by the first shell, wherein a nozzle extends from the front chamber into the entrance of the ear canal; and an in-ear portion comprising: a body having an upper portion shaped to make contact with the tragus and anti-tragus, a surface that rests against the concha of a user's ear when worn by the user, and a lower portion shaped to enter the ear canal, the lower portion being not relied upon to provide retention of the earphone in the ear, which allows it to seal to the ear canal with minimal pressure, wherein a first void in the upper portion receives the acoustic driver module, the nozzle extending into a second void of the lower portion, the lower portion forming an outlet section, the outlet section providing a passageway for conducting acoustic energy from the acoustic driver to the user's ear canal, and a positioning and retaining structure having an inner leg and an outer leg, wherein the inner leg and the outer leg are attached at an attachment end to the body and attached at a joined end to each other, wherein with the in-ear portion in its intended position, the outer leg is urged against the anti-helix at the rear of the concha and the joined end is under the anti-helix; wherein the nozzle fits inside the outlet section and has a rigidity, wherein an outside dimension of the nozzle is smaller than the corresponding inside dimension of the outlet section, wherein the difference in dimensions provides a space between the nozzle and the outlet section of the body; the space resulting in an ability of the lower portion to conform to the ear canal, and the rigidity resulting in an ability of the outlet section to conform to the ear canal, without substantially changing the shape or volume of the passageway. a body having an upper portion shaped to make contact with the tragus and anti-tragus, a surface that rests against the concha of a user's ear when worn by the user, and a lower portion shaped to enter the ear canal, the lower portion being not relied upon to provide retention of the earphone in the ear, which allows it to seal to the ear canal with minimal pressure, wherein a first void in the upper portion receives the acoustic driver module, the nozzle extending into a second void of the lower portion, the lower portion forming an outlet section, the outlet section providing a passageway for conducting acoustic energy from the acoustic driver to the user's ear canal, and a positioning and retaining structure having an inner leg and an outer leg, wherein the inner leg and the outer leg are attached at an attachment end to the body and attached at a joined end to each other, wherein with the in-ear portion in its intended position, the outer leg is urged against the anti-helix at the rear of the concha and the joined end is under the anti-helix; wherein the nozzle fits inside the outlet section and has a rigidity, wherein an outside dimension of the nozzle is smaller than the corresponding inside dimension of the outlet section, wherein the difference in dimensions provides a space between the nozzle and the outlet section of the body; the space resulting in an ability of the lower portion to conform to the ear canal, and the rigidity resulting in an ability of the outlet section to conform to the ear canal, without substantially changing the shape or volume of the passageway.