No single best speaker here - they are built to different priorities, and the right one depends on your room, your sources and what you listen to.
| Area | Better | Why |
|---|
| Bass | A | Kanto YU4 digs deeper - 60Hz against 65Hz. A subwoofer would even that out. |
| Built-in power | A | Kanto YU4 has the bigger amplifier (70W vs 30W RMS). |
| Connections | A | Kanto YU4 adds phono and digital inputs. |
| Size | depends | Audioengine HD3 is easier to place; Kanto YU4 is bigger, which usually goes with fuller bass. Your room decides. |
| Expandability | depends | Kanto YU4: a sub output; Audioengine HD3: a sub output. |
| Price | B | Audioengine HD3 is cheaper - $349 against $450, about 22% less. |
A Kanto YU4 B Audioengine HD3
depends neither is better in the abstract - it turns on your room, your system or how you will use them. Only specs published for both speakers are judged; anything missing on either side is left out rather than guessed.
Which should you choose?
Kanto YU4 leads across most of the measured areas for a fairly modest premium, which makes it the easier pick if the budget stretches. Audioengine HD3 is the one to take if it does not. If a subwoofer is in your plans, the bass gap largely stops mattering - you would be crossing over above 65Hz anyway, which makes the cheaper Audioengine HD3 much easier to justify. In a large or open-plan room, Kanto YU4 has the cabinet volume to fill it more easily; in a small room, near a wall or at desk distance, Audioengine HD3 is the easier speaker to get right.
And remember what a spec sheet cannot show: how each looks in your room and whether the finish suits it, what dealer support and warranty are like where you live, and how they actually sound to you. If you can hear them first - ideally with your own music - that will tell you more than any number above.