IDA-8 is an extremely popular and award winning integrated amp. New users are welcome to read this long topic on audiocircle.com: http://www.audiocircle.com/index.php?topic=134697.0

When a device has a 12V trigger input, it is designed to be turned on when a 12V is detected. You can use any standard male to male 3.5mm (3-pin type) cable.
https://components101.com/connectors/35mm-audio-jack

The Tip section is +12V, the bottom Sleeve section is GND, and the middle Ring section is not used. Nuprime’s trigger design uses 3.5mm stereo cable pin 1 and pin 3. A mono trigger cable shorts pin 2 and pin 3, it can be used to connect the Nuprime device to another device’s trigger that only uses a mono cable.

Summary: If an amplifier “doubles” its power into 4 Ohms, it often means the 8-Ohm rating was “under-built” relative to the power supply’s potential. If an amplifier provides the same power into both, it means the power supply is being utilized to its maximum optimized potential at the higher impedance.
Refer to this guide: https://nuprimeaudio.com/power-impedance/

Summary: If an amplifier “doubles” its power into 4 Ohms, it often means the 8-Ohm rating was “under-built” relative to the power supply’s potential. If an amplifier provides the same power into both, it means the power supply is being utilized to its maximum optimized potential at the higher impedance.
Refer to this guide: https://nuprimeaudio.com/power-impedance/