SST Ampzilla 2000 v2 vs Son of Ampzilla II


Looking for something new to drive my Dunlavy SC-IVas and am considering SST's Ampzilla offerings. My preamp is an ARC SP3. Hoping someone with a bit more exposure to them could share what they'd consider the pros and cons of each to be and whether the 2000 monoblocks are worth the extra money.
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I ended up getting the Son of Ampzilla II from Underwood, but there is a faint buzzing. It is on both channels regardless of what preamp or input source. :-(
Reach out to EJ at W4S/SST and see if he has any suggestions.  I would try a cheater plug on the amp and preamp and see if that does anything.  
Hi! I've been using my SOA2 (220 VAC version) for almost a year without issues.

Dead silent from both unbalanced and balanced inputs. 

I use as source a Lindemann Musicbook 10 DAC/Pre, and speakers are Dynaudio Confidence C1 Platinum. 

Sebastian