The sound source system is the K series, a sound module version of the K11, the successor to the K4. I connected a MIDI keyboard and confirmed that there were no problems with sound output from MAIN OUT/PHONES, sound selection, and the operation of various buttons. The dials are also working smoothly without any numerical jumps! Accessories are as shown in the photos. (※The instruction manual has handwritten notes from the original owner.) In my subjective opinion, the condition of the main unit's exterior is quite good! ◇ We ask for no claims and no returns. ◇ Please understand that there may be scratches that are not visible in the photos.