The output of my K4004B is low when the signal input is low, like from an iPod. It does not drive my speakers at a high level. To increase the signal input strength, I tried two different small stereo amplifier kits to boost the input signal and act like a pre-amp (a 1W that uses the KA2209 IC and a 1 W that uses two LM386 ICs ).
The output signal from the K4004B was greatly boosted and drove my speakers quite adequately. However, unacceptable (and odd noise) was introduced. These pre-amps introduced “mains hum” on my speakers (unless run from a battery); and, most annoyingly, they even picked up RFI: if one adjusts the rheostat of the small pre-amp, you can actually tune to some FM stations and hear them through the output of the K4004B!
My question: is there a pre-amp that works with the K4004B that doesn’t introduce interference/noise?
