Issue #3 (gets HOT!): Another thing that surprised me was how HOT the T9 Pro became after a while (I guess those 11W need to go somewhere). The tubes are the first thing to warm up (but I guess that's expected from a tube), but the whole case gets pretty hot after a couple of hours turned on. I wouldn't say it's burning hot, but it's hot enough to feel a bit uncomfortable if you hold your fingers on top of it or on the sides for a few seconds. Other than that I think having a DAC and optical input is great (obviously at this price its a cheap DAC) - though I couldn't hear anything obviously bad. I had a few devices plugged in (and Volumio Mini PC via USB) and Airport Express (via Optical) and a Turntable via RCA and it was great to be able to switch with the provided remote control. Q: Why does the volume of the machine remain the same, but the sound level is different when connecting to different audio sources (for example, connect a CD first, then a mobile phone)? Issue #1 (Bluetooth): at some point I got some weird noises when using bluetooth, but I don't plan on using BT much in the feature, so I didn't spent much time on it. My Presonus also have BT and I think at some point my phone was connected to both, so it might have been some interference between the two. This only happened once out of two times I used bluetooth. With multiple digital audio inputs: Bluetooth 5.0 / USB / Coaxial / Optical / stereo RCA, compatible with most audio device such as phones, computers, tablets, TVs, TV, CD players etc. The perfect combination of DAC and amplifier, very suitale for audiophiles who have various audio devices.

The speakers haven't arrived yet, but I received the T9 Pro yesterday and I didn't want to wait any longer to try it, so I started fiddling with it with what I had available: a pair of Presonus Eris E3.5 monitors (I know, not really "audiophile material", but it's the best I currently have). I also compared it to a Motu M2 interface that I own. Convenient and works fine, iPhone sees it as "BT HIFI AUDIO". I tried 6-8 meters connection, worked fine. Overall, I liked the features, lots of connections, sounds really good to me. I ran it mostly with 55 - 60% volume and it sounded clear, lots of details, base, etc. etc. I am now completely satisfied with the Aiyima in my modified System 1 and am streaming with a smile. Everything is good and that little bit of tube sheen is highly desirable. I shall conclude Part I. In Part II I shall likely be using the T9 as Preamp in my Living Room System 2 (which is why I bought the T9 in the first place). For that I shall restore my original System 1, which would be a real test. The last A in ABA is always more important than the AB. Now for some tidying up:

In For One to Love, Cecile McClorin .Salvant sings an absolutely ravishing Le Mal de Vivre (original Barbara). She gives a completely new dimension to the song. The subtle use of inflections in her perfect French tests microdynamics.

I also have a 24V power supply that I might try later, if I manage to find a compatible connector. I'd expect results to sit in-between the other two). Out of the box, everything was well. Sound was pretty good. I was impressed. I briefly determined that everything worked properly. As there seemed to be no issues, I was eager to move on from this ad hoc solution. The M2 seems to be very flat and a bit "upfront". The T9 Pro seems more like a U-shaped signature. Perhaps with some added "reverb"? (it feels like I'm listening in a larger room with a slightly better instrument separation and not so upfront). How was the Company Founded Founder Mr Liu loves music but is not at all an audiophile. He was in other businesses before as Yima, so when he decided to enter this business he just added Ai, love in Chinese, to the name. You can see that in the photos. But he obviously had found the right people to assist him. A Completely Different Business ModelWhy is the same product sold under many different names? Mr Liu’s friend’s factory OEM’s for a lot of people. Perhaps, and I’m not sure, some of them have small design changes, but...More importantly, from what I understand, these brands, Aiyima, Suca, Douk, Nobosound etc, compete as well as cooperate. Some would re-brand something without hesitation (same factory) and use their own sales base. This is pretty unthinkable in the West. Grant you, the products are similar (a testament to the very high level achieved with cheap digitals now) and, if you ask me, there is not much room for breakthrough.THIS is a BIG JUMP. I used the exact same 3.5mm to RCA adaptor and MIT cable I use for my Meridian Explorer, through T9's AUX OUT. Of course, I removed the loudspeaker cables from T9's binding posts. Practical funtions to simplify use: with input selection and indicators, clearly to show the working status in real time; aluminum alloy case is specially designed, cool and unique to decorate your desktop space. The Decision Yes, call me superficial. I immediately fell in love with the SEXY (VU) meter! But, unlike some of you, I'd not easily give in! :-) Certainly I have no need for another amp (or so I thought). While the almost universal digital connectivity appeals, what seals the deal for me was the AUX OUT. I wasn't sure whether it is Fixed or Variable, but as some users used it for subwoofer it should be a Variable out. It is, and more on this later. Tone Control In this configuration, particularly with the USB input, I dialed up the treble a couple of notches (it is indented and the feel is good) to give a little more air on top. It is very effective. No need for bass adjustment as my Floorstander has excellent bass (in both extension, weight and definition). Remember the tone controls are in the digital domain and are “in circuit”, so there is no reason not to use them. Think of them as kind of like dithering, but this is more effective imho (I don't usually like the Filter manipulations and actually harbor at least a little contempt for high end digital products that offer a few to choose from). Finally I capitulated and connected the amp to the larger loudspeakers (still with the Mogami cables).

Now I see what you mean. OK. The Aux Out on the T9 and the T9 speaker output are synchronously controlled by the T9 VOLUME: you turn up the volume and both the volume of your main loudspeaker and subwoofer output will go up accordingly. This has NOTHING to do with the subwoofer CROSSOVER. Or, put it this way. the Subwoofer Crossover ONLY adjusts the sub and has NO effect on the main loudpspeaker. You hear a difference but that is ALL from the subwoofer and your main loudspeaker is NOT changed at all under any circumstances. Overall I love the retro look of the device (especially in a dark room) the tubes 'glow' and VU meter is great (though the meter isn't very sensitive - you have to play loud to see it moving). As a rule, don't forget to tell me what you use, and what do you think of the sound, and reservations if any!

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Editor: Regarding Length This article is very long ( Covid Revenge Review?), as per my usual style when testing things I am interested in, especially things that can be used in multiple ways. Regular readers and experienced audiophiles will more likely find the many details along the way interesting. However, the vast majority of readers, usually referred here by a Google search, may want to skip here and there, or even just go to the end for Impressions, Comments and Thoughts. Regarding Organization In contrast to my usual ways, Music Used and my descriptions of the rights and wrongs will have a shaded box near the end, and there shall also be a little Technical Info near the end. So far, the only time I have ran into an issue with the Aiyima T9pro handling the Optical input is on the Sony Carosels. If they removed the internal DAC they would lose Coax and Bluetooth options. A: If you use a power supply other than the original standard, please replace the power supply before testing. Many power sources on the market have large interference coefficient of the text wave, which will cause a large current sound. Being an electronics engineer (and one with a conscious for power efficiency), I had to include this :-) It's also where I'll spend more time, because it's where it surprised me more (and on the negative side). Preface Boys shall always be Boys (though better not be "Proud"), and we need toys. We are always itchy. But in my 1.5 years here in China, I had not bought a single item. Amazing, no? It's not surprising: I have so much good stuff both in NYC and HK that I simply could not use here, and I have always viewed my stay here as transitional. So whatever tempts me better be (relatively) cheap and cheerful.

Line (RCA) In I tested this briefly with the Electronic Keyboard on my desk. Sound is good, but quite different than through the Revox system (cabling are different), more like a Bosendorfer to Revox's Steinway. Shall test it more usefully with my CDP in Part II or III (which can also test the Coaxial and Optical Digital Inputs with Red Book CD 16/44.1). I'd say that combo of the Android TV, no audio Computer monitor, and T9 pro made a great little station. Editor's Note 2/2/23:Readers may be interested in this newly published Video of the Making of Aiyima T9 Pro. It shows in detail how an Aiyima product is made. These sound like a skip, but they are cyclic, and it's a drop of connectivity. I was able to see this occur on 2 different CDP-CX355 units in addition to the 2 different T9 pros.Out of curiosity I tested the power consumption and sure enough the device consumes much less power once it goes into this mode so its definitely turning stuff off internally when this happens.