A powered subwoofer needs a connection to the Sub output from a receiver (you don't need an extra amp between the subwoofer ...
At $1,999, the Technics HA-507 is a pure analog headphone amplifier and preamplifier with a balanced/dual mono configuration. Although TEAC’s Reference 500 series includes UD models that combine both ...
you should think of buying a head unit that has three sets of preamplifier outlets. These “outs” let your HU control multiple amplifiers and each set of outs includes plugs for the front, rear and ...