Hello Casio vs.Yamaha seeker,
Wk1800 has 76 keys ....the PSR540 does not
I rank the sound quality to Yamaha. However,
with the WK1800 having 76 keys and the disk drive makes a nice package. Here's a tip ....
Some of Casio's best sounds are near the end of the sound selection. i have the best piano to be sound selection 130 ! Not the 1st sound 000. When playing midi files , you can see the keys illumiate in the Display. As a learning tool is better with Casio !
If you need more info email me at oneils4@home.com or Call Guitar Center in Towson Maryland 410 821 5200 ask for Dan O