I have a pair of Zu Druids (soon to be upgraded to Essence

) and I am currently driving them with a Nuforce IA-7 with great results, but I'm interested in possibly trying tubes.
Any recommendations? I would like to have a unit no more than 12" wide, as I am limited on the placement. Yarland? Sophia Baby? Jolida? Any others I should consider?
What type of tube should I be looking for? SET? Push Pull? Any clarifications or recommendations would be greatly apreciated.