Hi Freddy,
I can see no reason why adding any of the Technichord options, will make the KN7000 generate significantly more heat.

However, playing the keyboard continuously at maximum volume, could contribute to greater heat output from the power supply components and the power amplifier modules, which drive the internal speakers. The extra power required to produce the increased current drive to the speakers, has got to come from somewhere. That 'somewhere' is the power supply and increased current demand on any power supply, normally generates more heat........
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Willum

After silence, that which comes nearest to expressing the inexpressible is Music.
Aldous Huxley
( especially when the music is played on a KN7000....)