Siblings in Monitor Audio's Apex series, so they share a family sound. It comes down to size, output and price.
| Area | Better | Why |
|---|
| Bass | B | Monitor Audio Apex A40 digs deeper - 50Hz against 60Hz. |
| Amplifier needs | B | Monitor Audio Apex A40 is more sensitive (90dB vs 87dB), so it goes louder on the same amplifier. |
| Size | depends | Monitor Audio Apex A10 is easier to place; Monitor Audio Apex A40 is bigger, which usually goes with fuller bass. Your room decides. |
| Type | depends | A Passive Bookshelf against a Passive Center Channel - a different job rather than a better one. |
A Monitor Audio Apex A10 B Monitor Audio Apex A40
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?
Monitor Audio Apex A40 has the edge on paper, though the margin is not large. The rows marked "depends" may matter more to you than the score does. If a subwoofer is in your plans, the bass gap largely stops mattering - you would be crossing over above 60Hz anyway, so judge these on the other rows instead. If your amplifier is modest, vintage or valve-based, Monitor Audio Apex A40 is the safer partner - the other will want more current or more watts to sound its best.
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.