I copied this review that a well-respected member of the Korg forum did. It is available for view there, so I think he wouldn't mind my sharing it.
"Hi all.
Just got to spend two hours with the Pa4X last night in my friends Studio under perfect listening conditions. For those interested, here are some of my thoughts from the point of view of comparing the Pa4X to the Pa3X.
First up is the boot times. While I didn't actually time the Pa4X, it's blatantly obvious that it boots way faster than my Pa3X.
The Capacitive Touch Screen on the Pa4X is a vast improvement over the Resistive Touch Screen on the Pa3X. It's super responsive and light to the touch. I didn't find myself actually having to repress the same option more than once when making selections, which is something I'd get caught for now and again on the Pa3X.
Generally speaking, the entire performance of the keyboard is way faster. I was doing a fair bit of setup for my friend, loading styles and so on, and to be honest, I don't remember seeing “Please Wait” even once on the screen? Going from mode to mode, page to page, its all pretty much an instant response. Clearly the Pa4X is rocking a much faster CPU.
When it comes down to the sounds themselves on the keyboard, you can easily see where the benefits of having a much larger amount of PCM data streaming comes into play. The new sounds are a massive addition to the Pa4X library, and a delight to play. I found myself actually playing with the O-Verb effect quite a lot, remapping it to sounds that didn't have it by default as it's such a silky smooth effect to play with. I think it was first seen on the OASYS PCI ? The Guitar library on this keyboard is also amazing. It's very strong, and in many ways even far better than my KRONOS, or so it felt anyway.
Styles, many I knew from the Pa3X, but it doesn't matter. The new styles are fantastic, I even saw that KORG included a small selection directly for the Irish market. I wonder do all International Pa4X contain those styles? Either way, this was an excellent idea. When it comes to styles, the Pa4X is really bordering on perfection. I can't imagine a situation where anyone would ever be disappointed.
Build Quality, it's classic KORG. Beautiful machined aluminium sides, full metal body. Absolute top of the line workmanship. In comparison, when you compare the Pa4X to something like the toyish full plastic body of a Tyros 5, you can't help but laugh. KORG simply have the best built flagship keyboards on the market.
The Pa4X is a vast refinement of the Pa3X, and a considerable improvement on every front. The only one logical improvement I think KORG can make to the Pa4X is to allow end users to stream their own samples. So I can only hope that in some future OS update that feature gets added, just like KORG did for the KRONOS."
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DonM