Any preamp will work well and the amp will takes on its sound. I have personally found the Audible Illusions preamps to work extremely well with this amp (L-1 or M3A) It warms the slightly lean sound of the .5 up a bit without sacrificing clarity or bass performance.
If you have a higher output source component, the McCormack TLC-1 passive line stage works well but I prefer the added drive of the AI.
If you have a higher output source component, the McCormack TLC-1 passive line stage works well but I prefer the added drive of the AI.