The tubes are in circuit for most of these style of amplifiers. They often use the tubes as buffers though. They use solid state for most of the leg work and the tubes are just there to add the characteristics of a valve amp, the secondary harmonics and such.

I really like the way you reviewed. Great job.

Got this in my recommended. Really like your videos. Subscribed!

I'm really pleased with it! Makes my LP120XUSB sound way better thru my Edifier speakers :)

Sounds rather good even over YT.

I just bought Fosi Audio bluetooth tube pre-amplifier + Fosi Audio 50wattsx2 TPA3116 amplifier (total price around $100). Sound amazing

good detailed video! Thank you!

Thanks for the review. I already have a little solid state amp so a I may just as get the passive version of one of these, seeing as it uses a solid state amp anyway.

Thank you for your review. I bought one on ebay for $62.99. I will receive the package at the weekend.

Bought one. Sounds great especially for $90.

Great video. This guy answers every question needed. Just a few questions required for my personal set up, which are similar to your setup, I am also running Polk audio treated at 150watts. Does your setup every clip out at max. I'm planning on replacing my 5.1 amplifier with this -mainly because I just want a simple 2.1 . I have a powered sub that I plan on connecting using the daisy chain method

Great video ... Can you tell me what Bluetooth codecs are available in it for streaming? For instance ldac? Do the tubes help with Bluetooth sound quality? Thanks!

Thanks for the careful review! Do the speakers turn off when the headphones are plugged in?

Bel video, io ho questo amplificatore da un anno e mezzo e suona molto bene, l’ho accoppiato con le elac debut 5.2 ho cambiato l’alimentatore e le valvole e sto usando la porta rca perché lavora molto meglio del bluetooth.. suona da dio, ci sono possibilità di migliorare cambiando il chip o la scheda? Per curiosità

Great review! Thanks! Did you ever try out the Aiyima amp? (it does look identical to the Fosi one) How did that work out for you? Also, wondering if you considered replacing the opamp with higher end ones, such as those from MUSES. Thanks a lot!

Good afternoon, thanks for the video! I use an internal Creative card to listen to my music from the PC on the headset. Do you think that adding this amplifier will make a difference in terms of quality and sound signature?

I just bought a LG tv and want a small amp like this to connect to Boston Acoustic bookshelf for a small two channel television sound system. Would you recommend this? We sit close and personal to display.

Great video buddy I’m looking to buy one. May I ask what speakers would you recommend

Polecam wymianę lamp na rosyjskie 6j38p - wtedy dopiero będzie porządny bas i przestrzeń !!!

Thanks for the video, I'm looking to buy this amp however by looking into amazon I saw t Douk Audio P1 that looks to be the same + USB, do you happen to know that unit? I'll be using mainly with headphones (X2HR and DT770 80ohm)

Could you please tell me the screwdriver size to unscrew the back ones?

Thank you for a through review. I was surprised how much better poor quality MP3 sounded through this amp and there was enough power for my bedroom. What tubes will give it a warmer sound like a macintosh has?

Is it possible to change the 2 op amp on this please ? Thank you for the nice review !

Hi, I am thinking about buying this Amp. I have seen that there is a T20X model too. Do you think it is a worth upgrade? Thank you for the video.

cuidado, yo tengo el mismo pero de otra marca y a los tres meses estube cambiando los tubos para probar el cambio de sonido como habia hecho un par de veces semanas atras, y en uno de los cambios de los tubos con el aparato apagado del interruptor pero conectado a la fuente de alimentacion, pues se escuchó un ruido y las luces azules se qencendieron estando el interruptor en of, y los tubos ya no se calientan y el sonido (que era fantastico para auriculares) ya no está amplificado, el lunes lo devuelvo, y mañana me llega otro igual que he comprado por que es fantastico. lo mejor es no tocar los tubos, y si se hace que sea con el aparato desconectado de la fuente, de todas maneras prové unas jan 54.?w de ge que todo el mundo aconseja , pero yo prefiero las que trae que son las 6j4? los agudos tienen mas cuerpo y los graves mas impacto y apretados y en general mas volumen.

One question please: I'm considering buying a tube amplifier. But I listen to all my music through bluetooth from Spotify and my phones are also wireless. Can I both transmit AND listen via bluetooth with these amplifiers?

Hello does the Fosi Audio T20 had a phono pre-amp on it? thanks. M

An update on this amp... I somehow missed the annoying loud thump when you plug in the power, as I had the toggle switch in the off position. The toggle switch does not get rid of the thump when using headphones, so very annoying and bad for speakers. I also started to notice loud clicking sounds on the speaker when turning on, this stops after about 4 clicks, this was not there when I tested. It was so annoying I sent it back to Amazon. I then ordered the same amp but made by Aiyima from AliExpress which was £20 cheaper. It has the EXACT same thump and clicking sound. Here is the speaker start delay circuit: kzfaq.info/get/bejne/pbt4adtlzd-dc58.html - and just to clarify, it's probably fine to leave the amp connected I believe the current draw is small. I prefer not to leave too many electrical items on in my house, also the toggle switch on the front works fine protecting the speakers. I just wanted to make my own speaker protector. I also looked into the 100v voltage booster IC used, it is the UC3843B that is commonly used for this type of thing. I actually made my own version of it for a tube amp that I'm making, the chip can output high voltages, I managed to get 360v when testing. Here is a video of the 100v booster I made: kzfaq.info/get/bejne/jdB7p6yh156xcZs.html

Hey quick question will it work with some dt 990 pro 80 ohms? Or will I need a different amp

So the amp cant be turned of any other way than unplugging the power? Was looking into this one but thats kinda a dealbreaker

Hello Friend! Will the tube have any influence on the sound signature in the headphones?

Would you say it's worth it over a it's identical solid state amp?

What vacuum tubes should I use for the best sounding amplifier?

worth upgrading the up amp chips?

Did you notice any improvement with replacing the tubes ?

Los op amp se desmontan con la mano? O están soldados?

6BA6 tube？

Be careful, I have the same but from a different brand and after three months I was changing the tubes to test the sound change as I had done a couple of times weeks ago, and in one of the tube changes with the device off the switch but connected to the power supply, because a noise was heard and the blue lights went on with the switch on, and the tubes no longer heat up and the sound (which was fantastic for headphones) is no longer amplified, on Monday I return it , and tomorrow another one will arrive just like I bought because it is fantastic. it is best not to touch the tubes, and if it is done with the device disconnected from the source, in any case I provided some jan 54.?w de ge that everyone advises, but I prefer the ones that are 6j4 ? the trebles have more body and the bass more impact and tight and in general more volume

Oh the non copyright music thanks to the Larry David's of the world

Fosi Audio T20 + Lompoo LP42... Tantissimo con pochissimo.... :)

Is this a pre amp then?

this is work to 18 to 20v battery or no boss

What is the Bluetooth pairing name? Thank you.

This is 100 watts yes?

L'ho appena preso, niente male la qualità audio, soltanto 2 cose non mi convincono: -Anche quando viene spento resta alimentato (dovrei misurare il consumo per valutare quanto impatta in bolletta) -Il jack cuffie é molto delicato, basta sfiorare il cavo, con una leggerissima pressione verso il basso che la cuffia sinistra non si sente più (provato con più cuffie) qualcun altro ha lo stesso problema o é difettato il mio?

Do you know if Fosi Amps actually utilize the tubes or are they just aesthetic and use transistors? I've heard that's the case with many sub-$100 tube preamps. Thx!

На выхлопе усилитель D класса в лампах нет некакого смысла

Does it still work?

а лампы для красоты ???

A Chinese scam, only the PRE-amplifier is assembled on the lamps, the output stage is a noisy transistor assembly TPA3116, which makes the presence of the lamps a decorative element.

Китайский развод, на лампах собран только ПРЕДуселитель, выходной каскад шумящяя транзисторная сборка TPA3116, что делает наличие ламп декоративным елементом.