I wanted to upgrade my audiovisual setup in my new house, and needed a small stereo amp, with just three specific features: an optical input, a subwoofer output, and a usable remote control for at least volume. After scouring the Amazon website, I settled on the Aiyima D03. While I have had mixed results when buying electronics from an unknown mainland China manufacturer, this product was the simplest one available with the right combination of features. I wanted the optical input, because my entire signal chain is digital: HDMI from the BluRay DVD/CD player, into the Samsung TV, out via the TV's optical port, through a Bluetooth transmitter (for using Apple AirPods), and then out to the amp. I also needed the subwoofer output to drive an existing powered speaker, and finally, the remote volume control was also mandatory. The product also supports Bluetooth, although I won't be using that.This product fit the bill perfectly, and I have been very pleasantly surprised by it. The D03 is truly tiny; the cord-bump power supply is actually bigger than the amp. While it has a volume knob and input selection controls, the remote provides that, along with bass and treble controls, input selection, and more. When I connected it to my Klipsch bookshelf speakers, I got excellent sound performance, and completely quiet operation, no noise or hum.The amp features a nice graphic display which unfortunately, and owing to the tiny size of the amp, cannot be read from more than a few feet away. No matter, in my application, I really don't need to see it, since I'll only be using the optical input.The product came with a Bluetooth antenna (which I won't be using) and an optical cable, but without the necessary AAA batteries (x2) needed for the remote.Despite the five star rating I'm giving this product, no product is absolutely perfect, and I do have a minor criticism or two. The binding posts for the speaker outputs are really tiny, and a challenge to use with my stubby fingers. They also won't work well with heavy gauge speaker wire, so it makes sense to use 18 ga. or smaller wire, and abandon the myth that speaker cable gauge has anything to do with sound quality, especially with nearby bookshelf speakers. The instruction guide is also rather minimal, albeit sufficient.Class D amp design, something which I did professionally until my retirement, is truly amazing, in terms of reducing the size and weight of amplifiers. While class D amps have their challenges, they have the advantage on not needing massive amounts of iron and copper for transformers, as well as big heatsinks. As for the power output, I never believe the power rating claims of manufacturers like these, because they never specify the conditions for such a test. However, suffice it to say that the amp is far more powerful than it needs to be, to drive the Klipsch bookshelf speakers.Of course, since I only just installed this amp 24 hours ago, reliability will be my chief concern, and I would reserve the right to edit my review, should things go pear-shaped. However, once past the infancy failure stage, audio electronics can run for a very long time; I once had a Technics receiver in my office which remained turned on continuously for well over 20 years, until it finally failed. We'll see if Aiyima holds up as well.UPDATE: I've had this product since last May, and bought a second one for my daughter in August. I'm knocking off one star, for a couple of small problems in both that might be annoying to users. First, the IR remote control has a particularly weak output... it requires pointing the remote directly at the amplifier, and unless there's a clear and direct view, it often fails to work. Second, the volume control, via the remote, is difficult to use; each 'step' results in a very small volume change, so it takes a lot of clicks to meaningfully raise or lower the volume.Aside from those two issues, I still consider it to be an excellent product.