Cheap And Discounts Dual OP Amp Board Preamp DC Amplification PCB DC Pre-Amp Amplifier Empty Board Module for NE5532 OPA2134 OPA2604 AD826 Wholesale. Buy Directly From Merchant Aideepen Applied Store. Enjoy ✓Free Shipping Worldwide! ✓90 Days Buyer Protection. ✓Easy Return. ✓Money Back Guarantee.