Do I Need an Active Crossover?

Let us start with the definition: What Is a Crossover?

An active crossover is especially useful when using smaller speakers and integrating a subwoofer.
It gives you proper control of the crossover frequency and sets the high-pass and low-pass filters accordingly. It also helps you with proper time alignment, so the mains and subwoofer play in unison. 

The result is a much smoother frequency response, much cleaner and clearer sound, less distortion, more amplifier headroom for the main speakers, higher SPL capabilities, and an overall more flexible setup that adapts easily to most rooms. 
Active crossovers have been around for decades in AV components but are now gaining more tracking in the stereo market. And that is a good thing. 
Companies like Sonos, Bluesound, WiiM Audio, Lyngdorf, NAD, and Yamaha have high-quality stereo components that offer active crossovers. Some even have room correction as an add-on. 
Another way is to connect an external DSP (Best External DSPs) in between your PreAmp/DAC and Power Amp to achieve the same result as with an integrated solution.

So from our side, there are only upsides to active crossovers and we recommend looking for components that have them when you use a subwoofer. 
With Tower speakers, the positive effects might be a little less pronounced but still there.