Review on 🔊 Zerone Amplifier Board: Enhanced 2-Channel HiFi Preamp for Desktop Sound Speaker - Upgraded Sound Mixer & Amplification by Lucia Sempf

Preamp received in good condition but there was no documentation. So I had no idea what the technical parameters were. Actually I didn't know what the power supply requirements were or the min/max input and output voltage levels. There is also a small on/off switch labeled "on" in the middle of the circuit board. turn on and off" but it's not a power button! So what does he do? I asked the seller if he could provide technical documentation but he didn't have any so he asked if I would mind shutting it down for a while wait for him to contact his supplier. A few days later the seller contacted me and said that the supplier didn't have any manual or other documentation for this preamp! My last resort was to search the internet. I have some information about an older version of this Found the preamp and a datasheet for the audio processor chip. Both proved useful. It turns out that a tiny on/off switch controls the sound chip and also toggles the sound "effect" on and off. That's it for me As far as I can tell the sound effect mainly boosts bass and treble, which has a really surprising effect on the overall bandwidth of the frequency response, I have to say, although I was disappointed that I bought the product without a manual or other documentation, the seller's communication with me was exceptional. He was very concerned about my problem and did everything he could to try and find a manual for this preamp. I would have sent it back and asked for a refund if I hadn't been able to find documentation online, but I didn't have to go that route. The preamp works quite well and is definitely worth the price I paid for it.