Linear Tube Audio UL+ Instructions Manual page 8

User Interface and Controls
The front panel features a power switch, input switch, volume
knob, and display. The remote control is able to adjust volume,
mute, and access a menu with more configurable options.
Remote Control
Up and Down Buttons: Volume Up and Volume Down. They can be
held down or used in a single step mode. In Menu mode, they
scroll up and down.
Left and Right Buttons: Unused unless activated in the menu to
function as Balance control or input selectors. In the Menu, they
act as selectors.
Center Button: Mute. When the unit is muted, there are two Xs on
the display. When in Menu, it acts as a Select button.
Menu Button: Enters Menu Mode. In the menu, this functions as a
Select button.
Play/Pause Button: Toggle inputs. [When held down for 30 seconds,
it will pair an Apple remote to the unit. Pairing confirmation
appears on the display when this is successful.]