Head-Fi is the place to go for advice. My advice is to look at Antique Sound Lab. I am using the HD-600 with their MG Head OTL Mark II. It makes the Senns sound sweet yet detailed. I can listen to them for hours. I wish now that I had spent a little more and gotten one of their similar pre-amps with headphone output. I would have made a small second room system by adding am amp and my new Von Schweikert VR-1s. Good luck!
