The Hafler HA15 is a high performance analog headphone amplifier that has been meticulously designed to provide an accurate picture of the source material no matter the impedance of the headphone in use. The design begins with a 100% discrete circuit that is completely void of IC's. Although IC's certainly have their place in cell phones and other devices where size is of importance, they invariably employ hundreds or even thousands of transistors to boost the signal then use excessive negative feedback to keep things under control. As the HA15 employs single transistors, negative feedback can be scrupulously added so that the phase cancelling effects are minimized. This results in a much more open and natural sound with virtually zero artefact. Connecting to the HA15 is done using gold-plated RCA connectors that will not tarnish, thus ensuring a positive connection is maintained. This is supplemented with a pair of THRU connectors to allow greater connectivity options when setting up the system. An abundance of power for the headphones assures the HA15 will gracefully handle any impedance from 8 Ohms to 400 without choking. To bring greater excitement to the listening experience, a unique Focus control allows the user to activate a matrix that simulates listening to speakers in the open air. In other words, where headphones typically isolate the left and right signals from each other, loudspeakers in a typical acoustic space are heard in both ears. The Focus control lets you dial in as much of the cross-talk to suit while retaining a distinctive left-right mix.