When is a subwoofer needed?
This a question we get quite a lot, and the answer is as always: It depends!
Movies, Games, TV?
For these use cases, we basically always recommend a subwoofer. There is simply nothing that beats a large woofer when it comes to deep bass and LFE track reproduction. Adding a subwoofer will also remove the toughest strain from your AVR and speakers by letting the subwoofer handle the deepest and most straining frequencies. This will free up power from the AVR, leading to more headroom and an overall cleaner sound.
What about music?
This is a little more dependent on your other equipment: If you use smaller speakers that aren't designed to cover the full frequency spectrum, you can definitely benefit from a subwoofer. Just make sure your electronics have either a subwoofer output or at the very least a pre-output. If you use an integrated amp that doesn't have pre-outputs, you would need a high-level to line-level adaptor, as these inputs are not present on Arendal subwoofers. If you're using the 1723 Tower speakers and you only listen to music; you will most likely be perfectly fine without a subwoofer. With that said: If your electronics have active bass management, you can still achieve even better results by using a subwoofer and crossing over at around 40 or 50Hz.