They are recorded line-out.

The EQ can help, but it cannot add what's not in there. For instance, a 16bit sound will be less detailed than 24bit, no matter how much the EQ will make it sound cleaner. Only the existing harmonics can be changed in level, you cannot introduce new ones...

The MZ500 does not sound that good overall. These videos were the very reason why I wanted so badly to get to test one and when I eventually did I was rather disillusioned. Yes, it has many features, it is a great keyboard, but the sound set still lacks the depth. It is shallow - the electronic sounds are ok, but when it comes about the acoustic sounds, something is not quite there.

The excuse is, of course, you cannot expect the same sounds as in much more expensive instruments. That is fair, but still, the facts are facts. Where it shines though is working with samples and that is indeed an area they could develop even more, stabilize and improve.

Anyway, I am all for a proper competition from Casio, I hope next time I hear even better results.

Too bad the Yamaha S770 was missing from this comparison.