Leaving my short testimony here in case anyone else is/was in the same situation:
As some of you may know, the Cort Space 5 is a good deal for the price in terms of overall quality, ergonomics and playability but it has one flaw: The electronics.
At first I considered simply replacing the pickups for the Aguilar DCB-D2 but I ended up installing a Darkglass Tone Capsule in it instead (for now, I'm still thinking about installing the pickups at a later point) and after playing until my hands hurt, my advice to anyone else looking to experiment and improve the sound of any bass that comes with the Bartolini MK1 pickups is to start with those.
It was my original plan too but I decided that ultimately I would change the preamp after seeing a couple (information is scarce) of people saying that a pre-amp change actually made the MK1's sound good.
It somewhat does but I'm a firm believer that you cannot polish a t*rd and I came to the conclusion that the Tone Capsule isn't doing anything that a bit of smart EQ somewhere in my signal chain couldn't.
The 2.8kHz and 500Hz knobs are very useful, though. But ultimately, the Darkglass Tone Capsule cannot cleanly elevate frequencies that the MK1's aren't pushing in the first place nor can it make them sound any less wholly and undefined in the lows.
I don't regret it because I was going to install a new pre-amp anyway and it was always going to be a Darkglass one, but I do wish I had started with the pickups.
Keep in mind your experience may differ, as I've seen online.