Recently acquired a pr of Merrill's Veritas monoblocks and thoroughly enjoying the sonic improvements they have brought. However, don't seem to have great synergy with my existing Simaudio Moon P-5 preamp - a bit too solid state sounding, IMHO. Was strongly considering either the Atma-Sphere MP-1 MK3.3 or NAT Symmetrical as a tube compliment to the Veritas, but have no listening experience with either pre. Any thoughts/experiences?