Can the Yamaha CK88 be used as a MIDI controller?

Yes — the CK88 has a 2-zone MIDI controller mode that splits the keyboard into two independent sections, each sending on its own MIDI channel with separate program changes. It supports USB-MIDI and traditional 5-pin MIDI. It is not as deep as the RD-2000's 7-zone control, but it is more than sufficient for most live setups.

How long do the batteries last in the CK88?

Approximately 4 hours of continuous play with the built-in speakers at moderate volume. Using headphones extends battery life to approximately 6 hours. The CK88 uses 8 standard AA alkaline batteries. A battery indicator on the display shows remaining charge, and the keyboard automatically dims the display to conserve power as the batteries drain.

Does the Nord Stage 4 have better piano sounds than the CK88?

Subjectively yes for most players, but the difference is smaller than the price gap suggests. The Nord Piano Library offers a wider variety of meticulously sampled grands, and the ability to swap sounds via the Nord Sound Manager is a genuine advantage. However, Yamaha's CFX grand sample in the CK88 is excellent — it is the same core sound used in Yamaha's $200,000+ concert grands. In a blind test at moderate volume in a live mix, most listeners could not reliably distinguish between them.

Is the CK88's key action good enough for classical piano practice?

The CK88's weighted action is good for a portable stage piano but not at the level required for serious classical practice. The action is lighter than a typical acoustic grand, and the key pivot is shorter than ideal, making rapid repeated notes more difficult than on a full-size weighted action. For classical pianists who need realistic practice feel on stage, the Nord Stage 4 or Roland RD-2000 EX are better choices.

Which keyboard should I buy if I am just starting to play gigs?

The Yamaha CK88. At $1,499 with built-in speakers, battery power, and a lightweight design, it gives you everything you need to play your first 100 gigs. The Nord Stage 4 is a tool for experienced professionals who know exactly what they need and will use the workflow advantages every night. A beginner will not outgrow the CK88 — many working professionals use it as their primary board.