Linear Tube Audio ZOTL40 Reference User Manual page 4

Quick Start
Remove amplifier from the box.
Check that the MONO/STEREO switch on the back is in the correct
position for your setup. (see Operating Modes for more
information)
Attach the power cable to the IEC connector and plug into an
outlet. The ZOTL40 Reference uses a Berning-designed auto-
switching power supply and can be used universally.
Hook up your source and speakers.
Once your system is set up and everything is plugged in, turn your
system on. The Z40 Reference is powered on and off via the toggle
switch in the center of the face plate.
When first powering on, the tubes can take 30-45 to warm up
before music starts playing. Sometimes there is a high-pitched or
distorted sound during this time. This is normal and will go away
once the amp is warmed up.