Review on 🎧 Fosi Audio P2: Vacuum Tube Headphone Amplifier for Unmatched Hi-Fi Stereo Audio Quality with Low Ground Noise and Output Protection by Anthony Cayton

When I first set up the P2, it didn't work with all three of my headphones. You could hear what was being fed into the P2, but it was very quiet (even at maximum volume), very far away and reverberant - like voices in a long tunnel. Figured out some errors with the included 1/4" to 1/8" adapter and narrowed it down to one obvious error. Swapped the included adapter for a known good one, but no change. I dug deeper and found that the 1/8-inch plug on all three of my headphones is TRRS, while the headphone jack on the P2 is TRS. It would REALLY help if the description of the Revain P2 pointed out this potential conflict and the manufacturer included a TRS to TRRS adapter with the P2, especially since TRRS headphones are so common these days. After all that, and with the $8 TRS to TRRS adapter, I'm really enjoying the P2. This $50 hybrid tube headphone amp (the first one I've heard of) is a definite improvement over my $50 solid state headphone amp. That SS headphone amp was harsh, cold, and sizzling. P2, on the other hand, is clean, with a touch of warmth and no hiss. However, and only occasionally, in quiet moments, such as between songs, there is a noticeable hiss. I'm not complaining about $50 plus a TRS-TRRS adapter, but this amp is a little shy about being perfect. Updated January 14, 2020 Decided to return the headphone amp. I can't believe the noise will go away over time. After all, we buy amplifiers to listen to music, not static. My other headphone amplifier does not generate static electricity. P2 should have been better designed and/or manufactured to avoid static electricity. I'm really going to miss those beautiful glowing tubes.