Information about KN2600 is different if it come from a KN fan or a Yamaha fan. It is always the same history.
Yamaha fans tell PSR2100 is a lot better in sounds, styles, support,... and vocal harmonizer, etc.
Technics fans tell KN2600 is a lot better in all (sounds, styles, building quality, keys) except vocal harmonizer.
I read that Yamaha 2100 has similar sounds than Tyros (and I can tell you it is true), but KN2600 hasn't similar sounds than KN7000 (hasn't soloist sounds).
My feeling is: PSR2100 is much more similar to Tyros (O.S., sounds, styles, keys, harmonizer) than KN2600 to KN700.
I would like to know if really KN2600 sounds are similar to KN7000 listening both at external amplifier and loudspeakers.