Take them both home and try them in your system... This is the best advice I can give you.
They both are great units... Of course, I am biased towards the Passion but your ears should make the decision.
Just one thing, listen to both amps at different volumes. The amps may have different audible characteristics when played at different volumes. For example, the Plinius may sound great at low volume but may sound very harsh at higher volume level. On the other hand, the Passion may sound less involving at low volume but sound much nicer than the Plinius at higher level. These are only ficticious examples but these are factors that have to be considered.
Just me 2 cents
They both are great units... Of course, I am biased towards the Passion but your ears should make the decision.
Just one thing, listen to both amps at different volumes. The amps may have different audible characteristics when played at different volumes. For example, the Plinius may sound great at low volume but may sound very harsh at higher volume level. On the other hand, the Passion may sound less involving at low volume but sound much nicer than the Plinius at higher level. These are only ficticious examples but these are factors that have to be considered.
Just me 2 cents