Review on 🎶 Fosi Audio P1 Tube Pre-Amplifier Mini Hi-Fi Stereo Buffer Preamp 6K4 Valve Vacuum Pre-amp with Adjustable Treble and Bass Tone Control for Enhanced Home Theater and HiFi System Experience by Tiffany Young

Probably the cheapest and best upgrade you will ever find! My system is an old Denon 3803, some Infinity R162 bookshelves and an Elac s10eq subwoofer. Stream from Alexa Echo to preamp and then to Denon. I bought two different brands/preamps. both are high quality. I prefer the Fosi for its simplicity and RCA inputs, plus it's a bit cheaper. I've never tried standard tubes but replaced the tubes in the Fosi with vintage 1974 GE NOS tubes, the clarity of the sound was the first thing that struck me. It gives the music an airy feel but sounds cleaner. Of course, I've noticed things about some of my favorites that I've never heard before, especially the vocals. Harmonious nuances that weren't there before. I wanted to isolate any placebo effect. So I connected the second Echo directly to the Denon on the adjacent input source and played both simultaneously in the group. The transition from Fosi to direct source was abrupt. The increase in volume compared to Fosi was about twice as high or more. After adjusting the volume on the Fosi with a decibel meter to match the non-preamp input, switching between the two was easy and immediately obvious. I added a second preamp to my main cinema system without changing tubes. It also sounded fantastic, although for the price I would have bought better tubes in a heartbeat. Overall I would say given the declining returns in Hi-Fi. This gives you a quality boost that you won't believe until you hear it for yourself. It exceeded all my expectations and even my hopes. Amazing product!