Having recently retired I find I no longer need or use my HeadRoom "Little Version" headphone amp and its connected "More Power Supply" that I used in my various cubicles. I would like to sell them, but I have no idea as to what a realistic asking price would be. Any suggestions will be...

I would like to receive opinions and/or suggetions on which headphone to use with my (newly acquired) Antique Sound Lab MG Head DT OTL MKIII. Most listening will be done to small groups: classical as well as acoustic singer/songwrter, etc.. 'Phones on hand now are Senn 580 and Grado SR60...