Turntable technology peaked in the mid-80s. The advent of CD and digital meant that R&D evaporated. The so-called "high-end" turntables today do not compare to what you could get back then. Look at specifications if you don't believe me and be wary of anything without them.
Here are some wow and flutter measurements for my old Clearaudio Concept:
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It's nothing special, and frankly poor compared to something from the 1980s. This is a $2300 turntable. Sign up at vinylengine and download the manual for your Dual. The specs are probably better. (But this doesn't mean it can't be cleaned and serviced for optimal performance.) That said, this should all be inaudible. Some people say under 0.1% and others under 0.06% are the limits of human hearing.
Here is a Sony PS-X50 I got for $80. I am in the middle of a restoration and it will improve. This is it still "off."
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If you want something "good" these days you are going to have to get a Technics direct drive turntable. They are expensive now. But is it worth it?
This returns us to your question: that depends on many different things. Is your tonearm compatible with your cartridge (in terms of effective mass and compliance, for example)? How are you loading your set-up? Does your phono preamp allow you robust loading options or is it simply set to 47k ohms for example? These things affect the frequency response, which will alter what you hear. If you aren't thinking of these things you probably just want to buy something shiny and new. Isolation matters too as mentioned, but its issues are generally more obvious. More, Rega is not the way to go if that is an issue. The turntables are light and rigid.
This all being said, the medium doesn't compare to properly done digital. It's compromised and becoming obsessed with performance is a fool's errand simply because it'll never be perfect, there are too many things that can go wrong from a dried out belt to an off-center record. This doesn't mean you shouldn't try to learn about it. There are even a handful of members here with extraordinary set-ups, but they REALLY know what they are doing. I myself engage in the technical discussions here (and stay the hell away from the why is vinyl better than digital conversations).
In the end though, I think vinyl is "good enough" and is certainly enjoyable, but don't look under the hood if you are a romantic about it. I am not going to hate on anyone for spending $2000 for a fancy turntable. Aesthetics are important too. But you aren't going to get anything that is a noticeable difference. (Though the speed stability of a proper direct drive can be worth it.)
Edit: This is all assuming you have a reasonably decent turntable to begin with. The market today is so damn awful and comprised of cheap crap churned out for a quick buck. Most are made from the same parts. I recently had to purchase a new turntable for a family member and was struck by the poor measurements of turntables under $400-$500--the stuff that gets recommended in popular sources. The specs of these would be considered poor in the late 1970s. I would certainly expect any higher priced turntable to sound better than these. The cheapest turntable I can recommend is the Denon DP-400, which is $500! Otherwise I'd ecourage anyone to buy a well-spec'ed vintage turntable from a reputable source because this new stuff is not worth the money. In short: upper and middle class have collapsed.