Dear all,
on Allo web site was published a tech document: ALLO AUDIO CARDS TECHNICAL DETAILS (Revision: 1.1 Release Date: 09 Aug 2017).
It contains all specs about Allo sound cards. On page 4, in Allo Piano 2.1 DAC section, there is a description on Device tree overlay and its parameters.
It is possibile to implement glb_mclk (the description is: This option disables internal PLLs of the DAC to provide better sound quality. This setting is to be used with the Kali Reclocker board, which provides the required MCLK).
On Volumio WEB GUI I can’t find any settings for piano 2.1 installed with optional kali board. Volumio player that runs on RPI3 + Kali is it capable to turn on this settings?
Displaying my config.txt file (running rel 2.246) I can’t find it. In this case my piano 2.1 is working with interal PLL and not uses MCLK provided by Kali board? 
Thanks in advance
Umberto
Hi Jazz,
many thanks for the link. I have done it.
bye