I found good results with a pair of Berning zh-270 monoblocs and a pair of Art Audio Quartets. I feel those have the minimum power for the Guarneri. You may want to consider a push pull design with zero or very low feedback. Some members feel the Guarneri really needs a good solid state amp with more than 200 watts to obtain fast transients. I generally don't lean toward the solid state sound, but I wanted to share their perspective. A compromise may be something like a kt90 100+ watt push pull amp with lots of current.
In summary, I think a good SET will sound beautiful, but slow. A powerful solid state will sound fast, but lose some of the harmonic beauty of that speaker. So, I'd look for a 100+ watt push pull with low or no feedback and a big power supply. Good luck. Jeff