Alesis Studio 12R Reference Manual page 14

Balanced +4 dBu line level sources: Professional recording and processing
equipment typically provides a balanced, 3-conductor signal output that is a higher voltage
(1.24 volts nominal level) than most synthesizers and stereo equipment. The Studio 12R's
[LINE IN] jacks are designed to handle these balanced inputs.
Balanced sources often feature XLR outputs. However, they should NOT be connected to
the XLR [MIC] inputs of the Studio 12R unless absolutely necessary, because the higher
gain of the MIC jacks gives you less headroom than the LINE IN jacks do (also, the source
could be damaged by phantom power if it's turned on). Connect them to the [LINE IN]
jacks using an XLR-to-1/4 inch phone TRS (tip-ring-sleeve) cable, as shown below:
If the proper connector cable or adapter is not available, +4 dBu line level sources may be
connected to the [MIC] jacks ONLY IF PHANTOM POWER WILL NOT BE
USED!!
Connecting a line-level output to a phantom-powered XLR input
on the Alesis Studio 12R may cause damage to the external unit.
Alesis cannot be responsible for any damages caused by this kind of
misuse.
The nominal trim setting for a +4 dBu signal plugged into a line input is approximately 11
o'clock (12 o'clock on the stereo channels). This will give you plenty of headroom to start
with.
Maximum levels: The maximum level the [MIC] jack can receive with the [TRIM]
control full counter-clockwise is +12 dBu before clipping, so there's only 8 dB of
headroom if you plug a +4 dBu line source into the mic jack. The [LINE IN] jack on
channels 1-8 may receive levels up to +32 dBu without clipping, a headroom advantage of
20 dB. The stereo channels may receive a +22 dBu (balanced or unbalanced) maximum
input.
Studio 12R Reference manual
Connections
13