Hello Anders,
Before we talk about lo-fi 'phones, let's consider a few ideas first:
Pianoteq's built-in limiter happens to reduce the signal when two things occur simultaneously: A) When the volume/dynamic range sliders are set too high .... for B) the amount of note-on velocity you are playing. Restated, it is possible that, when one plays with rather high velocities (consistently 100+) AND with high volume levels in the Pianoteq model that audio distortion will occur -- regardless of the quality of playback device.
From my own experience, if most of my playing is within, say, 30 to 90 note-on velocity values with only an occasional 110 velocity, I can leave the limiter shut off. If a particular piece requires me to play with consistently higher average velocities. then I use the Limiter.
If, as you say, when you are recording solo piano with the K1, why not try leaving the limiter turned on ... during the recording process ... and then go back and disable it when listening to your playback. Your ears will tell you whether the limiter should remain on or could be safely shut off.
* * * * * * *
Let's go on to the headphone topic:
When you listen to other peoples' recordings of Pianoteq performances, or of commercial piano recordings, ... do the high frequencies distort in your personal headphones?
If the answer is "No, it only occurs in my own Pianoteq recordings, but not other peoples' recordings", then logic would suggest that you have Pianoteq's volume/dynamic range sliders set too high. In other words, your playing characteristics (in the form of note-on velocities) are probably too "hot" for the given volume slider setting you are using. In such a case, possibly not even a limiter will help UNLESS you reduce the overall volume slider within Pianoteq.
If your answer is "Yes, it occurs also in other peoples' recordings of Pianoteq, and even occurs in commercial recordings" ... then first borrow a better pair of headphones and decide whether the cans are at fault. It is also possible you are over-driving your amplifier to clipping distortion -- in which case, the highs are the first to be noticed as distorting.
Obviously, this is not the end-all of discussions on this topic, but it might point you in a direction where you may help yourself out of this problem.
One last thought: If one admits to lo-fi headphones, would it make much difference whether the limiter was on in the first place? Just a thought.
Cheers,
Joe
