[Elecraft] KPA-1500: any distortion when operated at Low Power?

[RVZ]

Hi Guys,
 Wondering if anyone has measured or experienced distortion on a KPA-1500 when operated at low power, such as: 200, 400 or 800 watts?  I ask because sometimes I need more than 100 watts to make a Qso but sometimes it's fun to run the minimum power required to complete the Qso.  That said, I don't want to run the KPA-1500 at 200 or 400 watts if my signal is distorted.  Tnx & 73,  Dick- K9OM