Ayre QB9 Dac . Upgrade to the new QB20. Vs competition In the $4-5k range or less

Hello I am looking to find out regarding the New Ayre upgrade for All QB9 dacs to the New QB20 Dac 
i see 1 review and  reviews many times are in part swayed with $$.
how good is this new upgrade ,and how would the QB20  and Schitt Yggsdrusil stack up 
and compare with each other . For these are my 2 options , please do chime in ,Thanks much.