I'm currently considering some pre-amplifiers, and I stumbled upon a Sunfire Symphonic Reference pre-amp for a cheap price in Brazil. My other choices are the Quad 99 preamo, the Adcom GFP-750, the Audio Research LS3, the Jeff Rowland Consonance and the Rotel RC-1090. I can't find none other preamp around here, so choice must be made among these. Which would you recommend, and why? I need some gain on output, as my power, Mccormack DNA 0.5 is only 100w.