A generation apart: Triangle Borea BR03 BT is the newer design, against a 2011 model. Newer is not automatically better, but the older one is more likely to be discounted or near run-out.
| Area | Better | Why |
|---|
| Bass | B | Audioengine A5+ digs deeper - 50Hz against 56Hz. A subwoofer would even that out. |
| Built-in power | A | Triangle Borea BR03 BT has the bigger amplifier (100W vs 50W RMS). |
| Connections | A | Triangle Borea BR03 BT adds Bluetooth, phono and digital inputs. |
| Size | depends | Audioengine A5+ is easier to place; Triangle Borea BR03 BT is bigger, which usually goes with fuller bass. Your room decides. |
| Expandability | depends | Triangle Borea BR03 BT: a sub output; Audioengine A5+: a sub output. Audioengine A5+ sits in a wider range (6 models), so a matched surround system is easier later. |
| Price | B | Audioengine A5+ is cheaper - $399 against $599, about 33% less. |
A Triangle Borea BR03 BT B Audioengine A5+
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?
Triangle Borea BR03 BT is ahead, but only on 1 of the measured areas, and it costs about 50% more. That is a lot of money for a narrow margin on paper - Audioengine A5+ looks like the sensible buy unless something else about the Triangle Borea BR03 BT appeals to you. If a subwoofer is in your plans, the bass gap largely stops mattering - you would be crossing over above 56Hz anyway, so judge these on the other rows instead. In a large or open-plan room, Triangle Borea BR03 BT has the cabinet volume to fill it more easily; in a small room, near a wall or at desk distance, Audioengine A5+ 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.