If "upgrading" your crossovers would really make any difference dont you think SVS would have done so already in the initial design? Were not talking about a fly by night company trying to cut corners, SVS would not skimp on that area.
I disagree with your uncle.
As a studio owner and music lover for many years, I have upgraded a few crossovers— including most recently, the SVS Ultra Towers. The issue related to using quality components that replace the roughly $60 in cross-over components (latest estimate based on my sources as of 2022) that SVS uses in the Ultra towers, is the margin they are working with. SVS spends a fair amount on cabinet and drivers, leaving little for the crossovers. Film capacitors, air-core (especially on the mids and highs) and better resistors (NON-Sand-cast) made a HUGE difference.
The SVS Ultra towers had cheap electrolytic capitors, iron core inductors, cheap aluminum wiring and sand cast resistors. ALL of them needed to be replaced. While $1,000 per speaker may seem like a lot, I can tell you that even much more expensive audiophile and studio monitors (Focal, ATC, etc) use low cost components of substantially inferior quality to what you can replace them with. The issue is that the margin they work with on $1,000/per speaker pricing, is that the underlying markup is based is roughly 400-500%, meaning that they would have to mark-up a set of high quality compents that cost at least $450/speaker to around $1,800 for each speaker just for the crossovers.
While the drivers of the SVS are really decent, and the cabinet work and finish are excellent, using high quality audio-grade crossover compenents like the claim in the marketing gloss when they assert “no expense was spared”, would mean that they would have to double their customer pricing. Focal (Trio-11’s), which cost us about $9,000 a pair had similarly low-cost components, which benefitted GREATLY also from about $350/monitor cross-over replacements.
The audible difference is that the SVS Ultra towers now are better than our prior mains, which cost about $14K, and the crossover upgraded Focal‘s now blow away virtually any studio near/mid-field monitors, regardless of price. Here is one of many video’s on the subject, which may be helpful.