I purchased this little T9 amp in July on the advice of my good friend doctorjohn. You can read his original review here: https://cheaptubeaudio.blogspot.com/2022/06/aiyima-t9.html This unit is really exceptional. It can be purchased from Amazon or your favorite CCCP sponsored online marketplace for around $129 USD. It is worth every penny. I purchased it to use as a stopgap until my single-ended 2A3 project is completed later this year, but I have become so enamoured with it I wonder why one really needs anything more. At first glance, the T9 looks like many similar amps in the marketplace with a gaudy VU meter (it grew on me, it looks good in person) and bluetooth antenna sticking out the rear. Actually the sound of this unit is exceptional. For me the key indicator of sound quality in audio equipment is clarity. I will quickly define clarity as the intelligibility of sounds and their subtle relationships, the separation (individuality) of different instruments, the separation (individuality) of different sound recordings and the successful transmission of intonation in music. The T9 is exceptional because for a modern device costing what it does and offering so many features (Bluetooth, DAC, pre out, tone controls, remote control, etc) it possesses a very high degree of musical clarity. I have had a number of expensive amplifiers in the exact same system ranging from SET to push-pull to minimalist discrete transistors to minimalist integrated transistor circuits and the T9 beat them all in this criterion. I won't list the individual comparisons because you won't believe me anyway. Out of the box, it will offer a pretty agreeable and enjoyable sound just connected via Bluetooth to a modern smartphone, totally acceptable for a budget bedroom/office/living room setup. The included USB cable sounds quite poopy and I would recommend grabbing another cheap one (I like the Elecom USB cable from Amazon JP for $15). My personal use case for the T9 is as a high performance in a dedicated two-channel system with high sensitivity speakers though. Since I received it in July, I have been making a number of tweaks to all parts of the chain and they are all heard clearly through the T9. In July the sound was good but fatiguing after a few hours, possessing those 'soggy' class D transients that never really go away and get worse at high volumes. Since then I have switched from using the USB input to using the line in with the DAC of my Mac Pro. The internal DAC is one of the integrated JL do-it-all bluetooth DAC chips. It's more than serviceable, I just happen to have a high performance DAC, so I used it. I wouldn't expect all or even most external DACs to necessarily sound much better than the on-board unit. I also made a bunch of other changes to the systems cabling (nothing expensive mind you), tweaks to my speakers themselves, etc. and the strain at high volumes has virtually disappeared. It was really surprising to me how the T9 reflected every change made and never showed itself to be the bottleneck. I am really quite confident I could invite some SET aficionados over and convince them they were listening to a SE 2A3 amp if they closed their eyes. The T9 has verve, it is totally capable of sucking you into the music. I can't really give much higher praise than that. I don't get much time to listen to the big rig but I try to sneak away a few hours every weekend to spend with the T9. I imagine most people buying one of these is going to use it in a smaller system with bookshelf speakers and for that application it's already very good. For a high-end application where you can spend a little time to get the most out of it, it's an absolute killer. There's a lot of hype around this unit so if you want more audiophile descriptors or know more about specs I am sure you can find some mainstream reviews which go through that. I'm just here to tell you to not sleep on this thing in the context of a high performance system.