1) Sound:
- Pianos: Good Concert piano sound, excellent upright piano sound with convincing damper resonance effect. Same waveforms as the YC and CP.
- Electric pianos: only two (73s and 78s). Both very nice with the key noise.
- Organs: Pretty good organ simulation, from the waveforms, drawbars, perc, to distortion and Leslie. Go for the rotary B if you want a more real and meaty Leslie sound. It is better than the red keys to my taste, and I've been playing on these for 5 years. Totally usable for live performs, and even recording, specially if you're playing with more instruments.
- Synth, strings, pads, etc - usable, though not the best. The pad selection could be better, you'll probably want to edit them with the hands-on controls and effects.
- Bonus - Dx7 Eps are top-level
2) Keybed:
I'm not a key-snob, and I'm used to play on every kind of key (weighted and snth action), from an Arturia MKII to cheaper keys. I didn't bother that much with the Korgs' small synth keys that man people hate but I didn't like the MX49/61 keys - I found them too soft and extremely noise.
In comparison to those, I found the CK61s keybed excellent. It has some nice resistance whilst is still soft and suitable for organ playing, and it is very noiseless. I can practice at night without bothering my wife and daughter.
Indeed, I found myself preferring these CK keys to the fatar synth keybed from my Arturia.
3) Building and looks:
Don't wait for wood and metal at 990 eu. It has a strong, sturdy black plastic case - still, pretty light to carry on. It has a simple front, without the angle from the MXs (for what I'm grateful). The round corners soften the visuals. You'll like if you're into minimalist design.
The model would benefit from different colours - white, red, and orange, for instance.
Nice, vintage-like knobs. The drawbars could be better, but still are alike to Yamahas' organs.
The visor looks like the YC's and CP's and can be turned off. Pitch and mod wheels are plastic, but better quality than the Mxs, and nice to use.
4) Functions:
The good - Here the CK is unbeatable. Truly. Three free layers (you can have anything, you're not stuck with the organ on the first layer as the competitors), you can control the three with an external controller - so, no issues like losing the layering if you want to control the CK with an external electronic piano. And you have a lot of flexibility on what control with what - assigning zones and midi channels, layers and splits - doing that is intuitive and not complicated at all.
There is too much to praise here, but the board was evidently designed with the actual musician in mind. I see addressed the issues I experience weekly with other stage keyboards, such as the mentioned flexibility of midi controls, but also the easy editing of layers. There are independent effect for each layer, and editing them is straightforward - just select the layer and the correspondent lights will light on the effects.
You can assign different colours to the layers, making it super visual and intuitive when performing.
There are live controls for all effects, plus attack and release and filter (cutoff/ resonance).
You can also control two or three layers' effects at once.
You have stereo inputs for an external synth/mic/instrument with independent effects (including noise gate, chorus, reverb). It is possible to select line or mic, and there is a good range of level/gain.
Finally, there is a master eq on hand - and you can edit which frequency to change with every knob. But you also can add specific eqs to layers with the effects section.
The not-so good - someone can think I'm nitty-picking, but I'd like to control the Led luminosity. It can be done with the LCD screen, but not the less. They're super bright, and that can hurt a bit while performing at home at night. I keep changing the colours to find something comfortable, but there's nothing to do regarding the white leds.
Bonus - filming/recording with the Rec'n share app is a breeze. No more video editing, or recording audio and video separately. You get a boost for your socials.
Conclusion - this board has everything a gig musician needs for an affordable price. Yamaha got it right, but I hope they keep an eye on the customer feedback and provide small tweaks with updates.