digital combos, help, EMM labs, MBL, Weiss, Metron

Dear all,
I am thinking about getting a new digital combo.
I have a choice of :
EMM Lab DAC6 SE + CDSD SE
Weiss Jason + Medea
MBL 1621 + 1611 F
Metronome Kalisata + C2-A Signature tube DAC
Does anyone has an experience of them to be able to compare them ?
Could I mix DACs and Transports ?
regards
david