You have two main choices for DC step-down:
Linear Regulator: Inexpensive. Throws away excess voltage as heat.
DC to DC Converter: More expensive. More efficient.
You didn't say what the input voltage is (your 5A supply). You didn't say what the power requirement on the three output lines (4.5V, 6V and 9V) are. You did say 1.6A but is that one EACH or all combined?
Input (primar) voltage to my adaptor is 240V AC,
I need total current of 1,6 A.
4,5V output 200 mA
6V output, 350 mA
2 pcs 9V Outputs 400 mA each. (total 0,8A)
I hope I could still use 12V output where I need 250 mA.
Would it be posible to isolate those two 9V outputs?
I am running two guitar effects on each output (today I use two seperate 9V adaptors )
One pair of pedals is connected to front of guitar amplifier, the other pair is connected in amplifiers LOOP (ie in between preamp and power amp).
It get noisy when I run everything on the same power supply.