Hi to all who helped thank you.
The result (possibly a conversion to ALAC bug ?) but anyway I made it work based on suggestions above.
If I have a 24bit/48000Hz file on my NAS, update the JRiver library and then sync JRiver with the handheld, JRiver converting to ALAC without applying any JRiver DSP settings the iPod recognizes and plays the file perfectly.
If I have a 24bit/96000Hz file on my NAS, update the JRiver library and then sync JRiver with the handheld, JRiver converting to ALAC and apply JRiver DSP settings to down sample from 98000Hz to 48000Hz the iPod is updated with strange bits and bit rates and plays at half speed.
If I do the same as above but when syncing to the iPod from JRiver and converting FLAC to ALAC I aply the DSP setting in JRiver as to down sample to 44100Hz and all behaves on the pod.
In Summary:
If the files are already at a 48000Hz sample rate and JRiver converts them to ALAC without applying any DSP all works perfectly on the iPOD.
But if the files on JRIver are at 96000Hz they will not play if down sampled to 48000Hz using DSP, they have to be down sampled to 44100Hz.
And that is that