There are major design and feature differences between the Sunfire and the Classe preamps, so be sure you get the one that fits your needs. I haven’t heard either of these units, so I can’t comment on their sound.
However, I can recommend an excellent stereo amp for $1560. The Continuum Audio Stage is a real sweetheart.
Here are some of the comments audio reviewers made about this amp:
“Exceptionally good sound, characterized by a wonderful sense of space,
delicacy and resolution.”
“This amp can really put out the peak current!”
"Right out of the box the sound was wonderfully transparent, detailed, and
it had plenty of bass oomph. The bass is super clean and v-e-r-r-ry deep.
No boominess or muddiness here."
"Extracts that last bit of ambient detail in the midrange and treble that
only the best amplifiers are capable of delivering. The extra detail that
gives this amplifier its sonic realism does not come at the expense of an
overall enhanced treble."
“Very few amps measure this flat in their output impedance or damping
factor.”
For complete details on the Stage amp, see:
http://www.coda-continuum.com/product/index.html