Sorry if seemed stupid question, why most of people uses led driver?, I just tried like this and looks havent problem. each channel tested and got the same current abt 750mA and voltage stable at 22.5V. 2 parallel x 6 leds AVAGO white per series by universal SMPS power supply 23dc ( adjustable 21-28Vdc ) + resistor 2.7ohm 2W by smps PSU its more cheaper than common led driver. It has a bad affect ? Othercase by the same leds i use DC-DC led driver per series after SMPS but nothing different?. please advise me.