sub$500 amp for Magnepan .5QRs

Would like recommendations for a 2 channel amp for my Maggies. I use a set of .5's with a Denon 3600 receiver and would like to upgrade the sound of my speakers. I listen to mostly vinyl with eclectic musical tastes, that range from shakuhachi music to Pink Floyd to John Coltrane. My budget is under $500 and yes I would buy used! Tubes or SS?