Fosi AudioT20X Bluetooth Tube Stereo Amplifier Home Audio Headphone Amp 2.0 Channel Class D Digital Mini Hi-Fi Power Amp Receiver for Home Bookshelf Speakers with JAN 5654W Vacuum Tubes

I purchased the Fosi Audio T20X to power a pair of passive bookshelf speakers (Micca RB42) for use in my home office. Through the Bluetooth 5 connection, I’m streaming directly into the T20X unit. The T20X delivers an ample amount of wattage; I’m not having to go even halfway on the volume dial to powerfully fill an average-sized room. The sound is downright impressive! While I appreciate having the treble and bass controls on the unit, I find myself not wanting to fiddle with them as I’m getting plenty of sweet-spot fidelity, and the bass response is excellent. The amplifier/speaker combo is nicely delivering a phantom center, which adds a very pleasing dimensionality to the music. In addition to the Bluetooth connection, there’s a RCA input for including turntables/cassette/CD players, etc. The headphone jack sounded fantastic with my Beyerdynamic DT990s, though I was getting some unwanted hiss with IEMs when the Bluetooth was used, which was not apparent at all otherwise – so not a deal breaker for me. This is my first purchased product which includes tube amplification, and overall I’m very impressed with the results. Using the T20X paired with quality passive bookshelf speakers has produced outcomes that I normally hear in equipment costing hundreds of dollars more. A worthwhile investment.

The amplifier is cheap and sounds very well, super crisp while not harsh. Compared to an old AB class amp you'll certainly hear all the nuances of different sources, which can be good or bad, depending on how analytical of a listening experience you like.But the reason for my 2 stars is the absolutely baffling headphone plug design. If you plug a headphone the sound doesn't stop coming out of the speakers, and you have no switch to manually turn them off either. I don't understand the use case where you need to use headphones AND your speakers at the same time. Totally useless.The only way you won't be returning this item is if you need ONLY a speakers OR a headphones amp. Needing both is a dealbreaker.

First let me say that the amp sounded pretty good initially - after I added a digital equalizer. After burn-in and without the digital equalizer it's dull across the mid-range until the high end which gets a bit screechy. Not terrible for $80 but nothing to write home about. With more use the sound quality has started to get worse, muddier, losing definition especially on female vocals.The big design problems are: 1.) the speakers don't disconnect when you use the headphone jack. Stupid. If I have headphones on why would I want the speakers on as well? Useless for private listening. 2.) The tubes come complete with bent pins. Good luck trying to seat them. The design of the top of the unit means you're working totally by feel because you can't see where the pins are supposed to line up. (Which you is a problem since you can't feel.) There is an easy design solution (bigger hole and removable protective washer) but they choose going cheap and saved at most 25 cents.I'm returning mine because of the sound quality and the inability to use headphones without waking up the house.

The media could not be loaded. Well, I am very impressed with this amplifier. The fit and finish is done really well and the weight of it is nice, it stays in place and the cables don't dictate it's position.At first listen, it sounded a bit thin and lacking in power. I am used to tube amplifiers needing to warm up, and have others like this that don't need as much time. It must be the particular tube they selected just needs a bit more warmth to wake up. At about the 15-20 min time things changed dramatically, lots of power, bass, and dynamic range. Where I had been listening is about the 1 o'clock position on the volume, now the same volume was at the 10 o'clock position. As time went on I continued to turn the volume down. I don't know if it was just because these were brand new tubes, but the second time I used the amp, the change was not as dramatic, the sound was pretty good from the start.You can see in the video, the volume is at about the 10 o'clock position and it was pretty loud in the room, and a comfortable listening level is at about the 9 o'clock. The sound is from the Energy C-300 speakers, a 6" two way tower, 8 ohm and about 88db efficient. Once the tubes warm up, this amp has tons of power. The volume control is very predictable and allows for a very soft volume level at the onset, and then ramps up smoothly. I did find the 'Line In" to be a proper line level input, it was able to handle all my devices input levels without distortion. The BT level was a bit quieter than the line in, but that could also be my BT device.The power on light at the front turns from (Red for Line In) to (Blue for BT), this is a nice visual que to what the amp is expecting. There is no way to switch between them, if the amp is detecting a BT "Paired" device it switches to BT even if you are using the Line In.The sound is warm and musical with a good amount of low end punch. Once the tubes warmed up, I found no need to move the bass or treble controls from the flat position regardless of the speakers I had hooked up.This is a very high quality unit for a reasonable price. I recommend this amplifier.