We present Auxtrument, a prototype instrumentthat allows audiences to experience the acoustic qualities ofremote locations. Using the metaphor of a reverberation chamber,artists send signals from the mixers, bus, or aux via theAuxtrument’s network connections from a concert hall to a fewdifferent locations. At each location the signal is played throughloudspeakers and captured, colored by the acoustics and noisesof the place, via a stereo or ambisonics microphone. The signal issent back and played for the audience in a surround sound systemconveying the spatial qualities of the places. The Auxtrumentallows us to merge and layer the different locations in the concerthall. However, this arrangement places great demands on thenetwork. The audio signals need to be high-resolution to preservethe inherent quality of the sounds, which creates large streams.The system must be equipped to work over different types ofnetworks, and to enable any location, the system must work withmobile devices. After ruling out several commercial and open-source solutions, we built the Auxtrument with web technologies:mainly node.js, WebSockets, WebRTC, and WebAudio.