I'm somewhere in between the cable believers and deniers. I think cables do something. But for me, it's more like putting a touch of salt and pepper on an already completed meal. It will add a little seasoning to what is already there, but won't change the overall taste.I found tiny Final E tips, with a super deep insertion that matches the aardvark-snout design, gave the best sound and fit so far for me.
I also got an interesting assortment of tips from Penon, stashed with the complimentary 9th anniversary 2-pin cable (if you're not picking a free gift at checkout, you're missing out!) It's almost an experimental group of tips... there's a foam tip with a vented side hole, there's one wide bore that extends beyond the stem, effectively coating all the way up the IEM not just the nozzle. That one gave a great seal and sound with the Fan 2, but didn't stick in my ear at all with the Serial.
I've yet to have an experience that confirms cable rolling, each to their own ears, but tip-rolling for certain transforms what reaches the ear in sometimes very dramatic ways.
Tips are like taking a steak and dipping it into au jus; it's a fundamental change to the experience. When done wrong it can ruin it, but when done right it can heighten it!