Use of cost-effective ,New optimization high NE5532 OP-AMP. Model: NE5532. It can adjust the treble and bass frequency effect is very obvious, let amplifier and speakers with more reasonably. This is a mature classic design,New optimization,Double side FR-4 1.6MM PCB Material,Each from both acoustic and aesthetic point of view to consider,Whole board without jumpers,beautiful and practical!
eBay