Radial Highline Stereo: Carry a Stereo Rig to the PA in Full Fidelity

The Radial Highline Stereo is a two-channel passive line isolator, a pedalboard box that connects a stereo guitar or bass amp modeler to a mixer or PA using a pair of precision-wound Jensen 1:1 transformers. It converts two unbalanced 1/4-inch line outputs into two balanced XLR feeds, keeps both channels at full level, blocks phantom power, and breaks ground loops, all with no power of its own and two summing switches for stereo or mono flexibility. For the player whose amp-sim patches live and breathe in stereo, the Highline Stereo is what delivers that width to the audience without hum, loss, or compromise.

Why Stereo Amp Modelers Need Isolation

Stereo modeling patches use two line outputs to spread ping-pong delays, dual amps, and stereo reverbs across the field, but those outputs are usually unbalanced 1/4-inch jacks. Send two unbalanced lines down a long snake to front of house and each one loses top end and picks up noise, while the shared ground between the modeler and the PA invites ground-loop hum on both channels at once. The Highline Stereo treats each side independently, isolating and balancing both channels so the stereo image arrives at the console as clean and wide as it left the pedalboard.

Twin Jensen Transformers for True Stereo Isolation

Inside the Highline Stereo sit two Jensen JT-11-YMPC transformers, one per channel, each passing audio magnetically while breaking the electrical ground path between the pedalboard and the PA. That galvanic isolation silences ground-loop hum on both sides, and because the transformers are wound 1:1 they preserve the full signal level and a flat 20 Hz to 20 kHz response with distortion below 0.05 percent and a 112 dB signal-to-noise ratio. The stereo image stays intact, channel to channel, with none of the phase smear or level drift that lesser isolation can introduce.

Two Summing Switches for Stereo or Mono

What sets the Highline Stereo apart is its pair of summing switches. The XLR Sum switch folds both channels into a single mono XLR output when the console only has one channel to spare, so you never have to rebuild a stereo preset for a small PA. The Thru Sum switch works independently on the Thru outputs, letting you feed a single stage amp from both channels while the XLR outputs stay in stereo, or keep everything in stereo when the rig allows. The two switches combine to cover stereo-to-stereo, stereo-to-mono, and mixed monitoring setups without touching your modeler.

Stereo Thru Outputs for Local Monitoring

Beyond the two balanced XLR outputs that feed the PA, the Highline Stereo provides two Thru jacks that tap the signal for local monitoring. Run both to a pair of stage amps for a true stereo backline, or engage the Thru Sum switch to drive a single amp from both channels while front of house still receives the full stereo feed. It is the flexibility a stereo player needs to hear their rig on stage exactly the way the audience hears it.

Who the Highline Stereo Is For

The Highline Stereo is for the guitarist or bassist whose amp-modeler patches are built in stereo and who refuses to collapse them to mono just to reach the PA; for the touring and worship player running long snakes who needs hum-free, phantom-protected connections on both channels; and for anyone who wants Radial reliability and Jensen isolation in a stereo box small enough to mount on a pedalboard. When your sound is stereo, the Highline Stereo is the isolator that keeps it that way from pedal to performance.