Hi Roy!
I use also a CSP-170 to play midifiles and lightning keys. I dont know what you exactly mean with play simultanious timbres.
I write my midis using Mixmaster for SysEx-Coding and Cubase Elements 10 for all other To play on the clavi I use a iPad pro and be very happy about doing as a beginner on Keyboard-Playing.
To set the Voices I have build up the CSP-170 as a MIDI-Instrument using my File “Yamaha CSP-170.txt” beeing attached.
Please rename to Yamaha CSP-170.txt before using.
Inside are all Voices from the instrument as in the manual. A lot of work, but doing great.
I hope this is helpfull for you.
Sorry about my bad english.
Harald