Dspringham - I highly recommend Atmasphere with Zu. You can happily use S30 with the Superfly, and any other Zu 'speakers because the high impedance makes a perfect match for OTL. Unless you need the extra power of the M60 monoblocks, stick with S30 and go for an Atmasphere preamp first - I believe it outperforms any passive, but I AM biased because we represent Atmasphere in the UK and I absolutely love the combination.
DISCLAIMER - we represent Zu and Atmasphere in the UK. Hopefully I've not offended anyone by posting.
DISCLAIMER - we represent Zu and Atmasphere in the UK. Hopefully I've not offended anyone by posting.

