What kind of mixer amp, what kind of speakers? What kind of cable are you using to go from headphone out to the mixer? Are you running stereo?

First things first. If your mixer has mic ins and line ins on the same channel, don't use the mic ins! Use the line ins (mic ins are generally XLR, line ins are usually 1/4" TS/TRS).

You might want to check into your mixer settings. Generally, when getting a hot input signal, turn down the FIRST pre-amp on the mixer (the channel gain) as low as possible, and run the channel fader at unity (0) and the main output at unity (depending on the power amps and speakers).

Generally, when running from headphone outputs, yes, 25-40% of full volume knob travel is considered best. Cheap keyboards don't generally use ultra-high quality headphone op-amps! I'd start with 30%.

Let us know a bit more about what you are using, we should be able to fix you up OK. I use the headphone outputs on my BK9 all the time to drive my stage monitoring (while the main outs got to the powered speakers or mixer) and have no issues.

OK... Yes, if you have a mixer that does not have separate gain controls to the channel fader, you may have problems.

Obviously, if you run power amp main outs as high as possible, you could run the input as low as possible, but if you have tried that with no success, we may need to look at other solutions.

Personally, I don’t use a DI box because I don’t need one, LOL My stage monitoring takes my headphone feed out into its RCA inns without any distortion. Plus, I consider a DI box not a great tip, because most of those are designed to take line level and convert it to microphone level. However several companies, including RadioShack, make what is known as attenuating cables. This is a type of cable that will pad the output down. This may work for you.

However I am concerned that you do not find any way to get a clean signal. I presume it sounds fine on headphones, so there is no distortion in the signal to start with? Admittedly, I use a BK9, which may have a better quality headphone amp, but I would not be too sure about that. To be honest, we have not had this problem reported before, and the same outputs that you use presumably being used by everybody else that uses a BK3.

I think the least expensive solution may be attenuating cables. But I would still check to make sure that the output is clean in the first place by checking on headphones…

I have one last thing you might want to check...

What kind of cables are you using? The BK-3 has a TRS stereo headphone out. But if you are using a 1/4"TRS to 1/4"TRS cable to plug into ONE mixer channel, the mixer may be expecting to see a balanced mono signal on a 1/4"TRS jack. This may well lead to distortion.

You will need a stereo 1/4"TRS to 2 mono 1/4"TS splitter cable, and use two channels (or a stereo channel with 2 1/4"TS inputs).

OK, I'm kind of at a loss at this point. Admittedly, I don't think I've ever used a BK-3, but I find it surprising that you are getting this much distortion. I know my BK-9's headphone out is pretty clean at least until 60% of full output when run into either my stage monitoring (usually Mackie SRM150's, but also tried on QSC K10's) or my digital recorder (Zoom H4n). I usually run at 50% and everything's clean as a whistle.

Any chance of borrowing someone else's powered mixer/amp and checking to make sure it's not the mixer/amp? If possible, I might check that before you go and try the attenuating cables or a line pad/DI box. If the problem is in the mixer, none of that is going to help. If you can't get the sound clean by turning down to 10% and under, I doubt the attenuating stuff will help.

As to a 'better' piano sound at higher velocities, try adjusting the Key Touch to 'Low', which will make the higher velocity sample sound when hit softer. Are you a piano player, or have you come to the BK-3 from an organ or accordion type background? I have never really felt I need to strike any keyboard 'really hard', but I do come from playing piano and Rhodes', etc., so my touch is probably a lot harder than accordion or organ, which aren't velocity sensitive at all. And, again, I've never tried the BK-3 keybed. Can anyone who has tried both say if it's any significantly different to a BK-5 (which I have)?

You can also force the Part that is playing the piano into a 'Fixed' velocity, and can set it high enough your higher velocity piano sample plays all the time, but obviously you lose any dynamics at all. But if from an organ/accordion background, you may be used to that...

But until you have a clean signal to listen to, any adjustments right now may not be what you are after.

Last thing to check... Turn off all the Mastering Tools stuff (the EQ and compressor) and see if that helps clean things up. Personally, I am not a fan of what they do unless playing into pretty poor, cheap speakers. The default settings tend to hype the lows and highs, which might be pushing your rig into distortion.