You have endless amp options and yes, older Pass amps are fantastic with Zu. I believe the First Watt F3 would be a good choice. A more expensive choice, but one that is great is a XA 30.5 or the new J2.
As for tubes, there are many choices that will give you great bass. There is a Mystere amp for sale right now that would work very well with your speakers. Another great choice would be a Decware Torii or a Melody amp.
Good luck on your choices.
As for tubes, there are many choices that will give you great bass. There is a Mystere amp for sale right now that would work very well with your speakers. Another great choice would be a Decware Torii or a Melody amp.
Good luck on your choices.