John Cale used this instrument on the European 2003 tour. From Wikipedia:
The K2600, released in 1999, improved on the K2500 with the addition of a new effects engine called KDFX and an enhancement to the V.A.S.T. engine called triple-mode. KDFX was also offered as an upgrade for the K2500 and later made available as a standalone product in the KSP8. KDFX drastically improved the quality of effects over the K2000 and K2500's built-in effects units, and added more flexibility such as using the Kurzweil as a vocoder. But the most impressive feature of the K2600 was Kurzweil's 'Triple Strike Piano', which was one of the most realistic-sounding sampled pianos available at the time. Patches for the K2500 were completely redesigned to incorporate the KDFX and triple strike capability. The K2600 uses different type sound expansion ROMs than the K2500 (although they contain the same samples), and could have a classic keys and General MIDI (GM) sound set added.