I've had very good results using a Jolida 102b (factery mods) with my Europa Max's... I'm considering moving up line for a little more power and a remote perhaps the 302BRC.
Don't let Jolida's low entry pricve fool you. With the right tubes they sound far better than they should (for the money). That being said I've got a pretty good DAC in the mix as well.
Hopefully I'll beat you to the Callistos... ;)
Enjoy the tunes.
Tony