i got a fosi audio t20 tube amp. it rocks! no noticeable noise floor, and clean to max volume. doesn’t distort at the end like my sony receiver for instance(garbage in hindsight lol). the headphone out on it works rather well, tho it has some noise with my iem’s. headphones seem alright on it tho.
on a side note, i missed this thread. going to see if @M0N can move that review to this article and merge the 2?(sorry M0N)
This is an unofficial review of the Fosi Audio t20 mini tube hybrid amp. Retail price: 85.99$ currently with a 10$ off coupon on Amazon as of writing this review.
I am in love with this little amp. I have 0 qualms recommending it to anyone as a starter headphone/speaker amp. It has no built in dac, but it does have built in bluetooth. This could easily be any ones starting point into the world of hifi audio.
Little bit about the specs. 50 wpc class d CLEAN amplification. I like it at least as much as my sprout100. I have hardly used my sprout100 or the subwoofer connected to it since getting this bad boy. The headphone out I can not find specs on, but it seams to be fairly powerful. It drives my t60rp argons to loud levels, but does not sound quite as good with them as my lyr 3. All my other headphones tho that are not as demanding, I can not tell a difference between it and my lyr 3. It has a really good headphone out.
The stock tubes do good. They are fairly clinical and not that “tubey” sounding. They do an adequate job. I personally replaced them with Riverstone audio’s NOS ge 5654 tubes. They are a little bit warmer and wider in the presentation. But if you like more of a clinical tuning, the stock tubes will do good.
The bass and treble controls work really well and they have a good focus point for each. While I do not have measuring equipment, and can not find specs, I did find a similar fosi tube preamp with the same controls. On that preamp the bass was set to slope up @ 500hz on a sliding scale. The treble was set to 2k on a similar slope. This amp seams to follow that same pattern so I will go with it. Gives you roughly 12b ± at max gain adjustment for both. Mind you on a sloped scale, so +12db at like 30hz and more like +3db at 500hz when maxed out bass for instance. It is a failry level slope tho with no peaks and valleys. So it works well in implementation. Don’t get me wrong, it will not replace a 7 band+ equalizer, but its good for what it is.
This thing is rated at 50 wpc but it feels more tbh. I have yet to go past 12 o’clock on the dial with my martin logan speakers. And that was just for testing purposes as it was insanely loud at 12 o’clock. My usual listening is between 2 clicks and 5 clicks(5 clicks is 9 o’clock). The volume knob is good. Wish it was a little bit bigger. But it does have a fairly satisfying clicking resistance movement to it.
The tube sockets have blue leds in them that causes the tubes to glow blue for 80% of the tube until the filament where the orange glow takes over. May or may not bother you, I am not a big fan, but I can overlook it as I do not stare at my amp all day anyways.
All and all I am really impressed with this little guy. Bought it on a whim to see how it would perform and if it sucked, was planing on using it as a tube preamp for garage speakers. But I feel its to clean and to good for preamp duty. After playing with it some more, I will replace the soundbar(ick) in my bedroom to this + speakers.
For a simple plug and play mostly(no dac) all in one unit, this is a great option. You can hook it up to a pc or stream from your phone and not need any other equipment. Some of these cheap in price but not sound quality chifi amps are a real bargain. How they stand the test of time who knows? This mini amp is built solid by appearances tho. Has aluminum body and a very thick solid plastic face. Comes with mini isolation feet that as far as I can tell work well to not let the tubes pick up vibrations. Granted I have mine on a mini audio rack, so that isolates it as well. But even on the floor it was not picking up anything on the tubes.
One thing to note: When i have it hooked up to my 2 ways with a 10" woofer, I have to crank the volume up much more to get the 10" woofer going. I do not think this would work well for medium+ room’s. But for nearfield or smaller rooms, this is a knockout! Just watch the size of the woofer you are pairing with it. Unless you have some ungodly efficient speakers like klipsch heritage series, I would stick to 6-7" woofers or smaller to get the best out of the amp and speakers.
This may have been the worst review written lol. I feel scatterbrained and all over writing it, but I love this little amp so much I just had to give it some love. I highly recommend it for nearfield/smaller room listening.
That’s good to hear you are enjoying it. 
A bit over 2 years ago when I decided I wanted to really play with home audio I too started very inexpensivelly so I could slowly dip my toes and understand all the differences in gear folks were talking about all over the internet. I traveled to different stores to listen to what I could and finally began my journey with a tiny little SMSL AD18 amplifier and some excellent monoprice Kbas speakers. I have upgraded and added all sorts of gear since then but still to this day, continue to use all my original purchases because; I both enjoy what they offer and the noticeable changes between those and multi thousand dollar set-ups only count to me when I’m listening critically and have the inclination to sit down long enough to appreciate the differences in quality of sound. I now have speakers and amp all over the house and enjoy myself immensely. Good write up, nice to see more folks doing what they can to tell us more about what they have, makes it easier for folks to make better informed buying decisions. Happy listening always!
It has been moved
thanks a lot!
I just got the FX Audio Tube-03.
First impressions, after the first hour.
Volume: If you turn the volume higher than 12 o’ clock, expect a ton of distortion.
Bass:
-If you don’t put the bass knob at 11:30 
or more, expect a total loss of sub-bass.
-It’s like the bass knob “starts from 0hz”. Turn it left all the way and it will erase everything from 0-200hz.
-If you turn it right a little bit, expect a pleasant bass boost. As if my T50RPs needed more bass… but here it is.
-More than half (12 o’ clock), and re-live the disgusting Honda Civic era of people with loud and shitty, distorting subwoofers in their trunk.
-But if you want, you can bass boost the crap out of everything and get a “old Beats by Dre simulator” by lowering the volume knob to 1/4 (nine o’clock? 
) and then turning the bass knob to the right. No distortion.
Treble:
-Maybe three clicks left again, 11:30-ish
-Well, that’s a surprise. Even with the knob all the way down, I feel like the Tube-03 adds a ton of “air” (10khz+) to everything (no “esses” sssibilance – higher than that!). Where the bass knob was just, basically “erasing” all the low frequencies, the treble knob just “pushes em down”… but this 10khz+ “air” stays. So whatever you play, it never sounds muffled.
Other infos:
-Not microphonic. I.e., if I pause the music and knock on the casing, or even touch the tubes, I don’t hear anything.
-I’m actually stress-testing it with powerful, sometimes “wall of sound” electronic music. So if I don’t hear distortion now, you, jazz amateur, certainly won’t hear atrocious distortion.
-My first impression was, actually “hey, this sounds clean”. And this 30$ thing also adds soundstage.
I was expecting “tubiness” to be smoothness, a higher amount of bass, and muffled sound. I got a bass boost knob, “air” and soundstage, and apparently clean sound. Definitely worth the 30$ for me. 
I’d just recommend this to everyone who has closed-backs or open-back inexpensive headphones with drivers “dying” at 10khz. Maybe this can help.
I got Nobsound’s variant - under the name Doak Audio - back in August. I was similarly pleasantly surprised. I put GE JAN5654 tubes in it too. The sound is amazing. I completely agree it widens the soundstage. But I also notice that it fills in the soundstage, seemingly bringing the soundstage between L and C and R and C up so that there’s a more uniform presentation all the way across. It does add some warmth, too. What I can’t say for sure is if it’s adding any “tubey-ness”. I got in on the last Darkvoice drop and am excited to compare the two. I don’t know how long that will take to get here, and coronavirus is likely going to delay it further (that’s ok, we definitely should prioritize people NOT dying). When it does finally arrive, I’ll do a thorough comparison to see if these little buffers are actually doing “tubey-ness” or if they’re essentially cool looking tone controls.
Do your tubes stay in it well? The biggest complaint I have is that it’s easy to unseat the tubes.
Lol, definitely!
Huh, mine won’t move, they were a bit difficult to put in there.
I swear… I don’t know what this thing does or how it does it. But I guarantee that’s the best 30$ you’ll ever spend on audio. With headphones, this little thing, even just after powering it up, with cold tubes, can easily, easily give you this “holographic” experience, and make you go from “yeah, well, I’m listening to music” to “oh well, I’m there”.
A/B-ing (with headphones)… It multiplies all the little details. Multiplies the soundstage. Makes everything sound “airy”. Maybe not in a perfect way. But for 30$? Holy shit, I can’t wait to hear the enormous difference it makes to speakers. That’s my first tube (pre) amp. Some of you here are probably laughing. But for all the newcomers, this 30$ gem will definitely take your lo-fi gear and give you a taste of hi-fi.
Intriguing, I might give one a try.
Did the linear power supply you ordered make any improvements to the system?
Do you use this with the jds labs atom?
Has anyone tried the Little Dot Q+? It claims to be a class A dac/amp.
https://www.china-hifi-audio.com/en/little-dot-audio-headphone-amp-dac-c-59/little-dot-ld-q-hd-usb-dac-headphone-amplifier-vacuum-tube-transistor-hybrid-p-1846?zenid=c433501cd08b1826d357013e09977e61
The funny thing is, my Atom is still in repair. I heard all this from an AVR headphone out. So, quite impressive.
Let me know how it sounds paired with the atom amp when you get it back.
Probably even better. Like “I don’t believe I need detail monster headphones anymore, I know what it is now” better.
Obviously it messes with the frequency response. Obviously you won’t do mixing or mastering with that (…so I still need detail monsters, lol). And I guess people with 500$ tubes would say the Tube 03 “squashes the depth and replaces it with width”. But oh well. Still worth the 30$ IMO.
My hypothesis is these little Chinese tube buffers are underrated. I don’t know for sure, and that’s one (of several) reason I ordered the Darkvoice on the last drop. Someday I’ll find out…
I don’t have the same model @LeDechaine is using, as I state in a post above. However, they may actually be the same thing in a different box and with a different name. I’ve plugged into both an Atom and an SP200 and it made a huge difference on both. The Atom is nice because it has 2 inputs. So you can get a splitter and bypass the buffer to one input and route through the buffer on the other and switch back and forth at will (and underappreciated feature of the Atom, IMO).
Yes, I was thinking about A/B-ing with a splitter too. 
(Adds a splitter to his Amazon cart, lol)
Could you link me a splitter? Doesn’t matter if it’s good or bad, just want to know what one looks like.