I'm looking to buy a nice weighted DP, on the cheaper side. I've been looking at the Casio Privia series, as they seem to meet what I want. But the cheaper ones, such as the PX-120 and 130 don't have a 1/4" output to connect to an amp, mixer, or PA. They do have headphone jacks. I know there are adapters that can be used. I'm not sure the size, 1/8" to 1/4" right? The thing is, I'm not sure if they will work or not. Has anyone tried it or does anyone know if it will work? Thanks.

I'm not sure what size headphone jacks the 130 has, but regardless, you should be able to easily find an adapter (1/8 or 1/4" stereo to RCA for home equipment, 1/8 or 1/4 stereo to 1/4 stereo for others). Just be aware that the headphone level is not the same as line level so be sure to turn the volume all the way down and then adjust it up to get the right signal level.

People who work in professional audio will tell you "oh my gosh it will sound horrible" but the average person would never notice any problem. Those mixers and PA amps are actually easier to drive than are headphones. The only problem is if you turn the volume up to high on your piano and feed the device with more signal than it wants. -- don't do that and you'll be fine

Alright, I think I'm going to buy an adapter. Thanks!

Sorry to bring this back up and double post, but...

Has anyone actually tried hooking ANY DP up to a mixer or speaker through the headphone jacks? I want to use this (PX-130 most likely) for gigging, and don't want to see that after I have paid $400-$500 for this DP, it sounds worse than the on board speakers.

It can be done, but you would be introducing potential points of failure:
1. Many Y adapters are of low quality and can fail due to poor solder or damaged wires.
2. If the headphone jacks are the mini 3.5mm type, it is quite easy for the plugs to bend or for them to be pulled out - the points of contact are very small.
3. Some headphone preamps are of relatively low quality and can introduce hiss into the signal. You would need to be sure that the audio signal is of sufficiently high quality.

I don't think anyone would recommend this method of connection for use on a regular basis.

Maybe I should get the PX-330 then, since it has an output, plus loads of other features. I'll just have to hold off on a synth for now, but piano > synth.