These sit in different price classes - Buchardt A500 costs roughly 1.9x what ELAC Navis ARB-51 does. Expect it to lead on paper; the question is whether the gap is audible enough in your room to be worth it.
| Area | Better | Why |
|---|
| Bass | A | Buchardt A500 digs deeper - 25Hz against 44Hz. |
| Built-in power | A | Buchardt A500 has the bigger amplifier (450W vs 300W RMS). |
| Connections | depends | Buchardt A500 adds Wi-Fi; ELAC Navis ARB-51 adds Bluetooth. |
| Size | depends | Similar cabinet size - neither is easier to fit. |
| Cabinet | depends | Sealed vs Ported. Sealed is tighter and happier near a wall; ported digs lower but wants space behind it. |
| Price | B | ELAC Navis ARB-51 is cheaper - $1,998 against $3,850, about 48% less; arguably a different class. |
A Buchardt A500 B ELAC Navis ARB-51
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?
The usual trade-off: Buchardt A500 measures better, ELAC Navis ARB-51 costs about about 93% more% less. Whether that gap is worth the money is the call only you can make - and in a normal room it is often smaller than the numbers suggest. If a subwoofer is in your plans, the bass gap largely stops mattering - you would be crossing over above 44Hz anyway, which makes the cheaper ELAC Navis ARB-51 much easier to justify. Think about the whole system, not just the speakers: the roughly $1,852 saved by taking the cheaper pair would buy a subwoofer or a better amplifier, and either usually does more for the sound than the difference between these two.
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.