Ayre Acoustics K-5xeMP Stereo PreampAyre builds electronics in Boulder, Colorado with two commitments that don't bend: fully balanced circuitry from input to output, and zero feedback in the signal path. The K 5 is where those principles meet a preamp that the used market has been slow to let go of, which tells you something about how it sounds to the people who own it. The zero feedback design is the headline. Most solid state amplification applies feedback as a correction mechanism.