Audio A3 PRO 6K4 HiFi Tube Preamplifier — Tube Preamp, Bile Buffer Amp, Speaker Sound Amplifiers, Bass Boost

Important usage and safety notes for the Audio A3 PRO 6K4 preamplifier: 1) This unit is a preamplifier, not a power amplifier. It must be used together with a power (post) amplifier or an active speaker. Do not connect passive speakers, speakers or earphones directly to the power output of this preamp; connecting them directly (or using it improperly) can cause damage — for example, unstable voltage may even cause a car to burn if used in an automotive setup. 2) If the general wiring or power supply filtering in your setup is poor, the chance of low-frequency/base (bottom) noise is high. To reduce this risk, use quality cables and a stable, well-filtered power supply. 3) Confirm your source device is clean and noise-free before testing. The preamplifier will amplify any noise present in the input signal, since it performs preamplification itself. Always test with a good sound source. 4) Verify the vacuum tube is fully seated in its socket. Make sure the tube is properly inserted into the base and double-check seating, especially before powering up, to avoid problems on power-up.