Adcom 515 verse Monster 3600 or 2600 power conditi

I owned a Monster 2500 power unit for years then sold it for a 3500 which gave up the ghost two days ago. I am looking at at 3600 and a 2600 but in the meantime my brother gave me a Adcom 515 he had laying around. From a sound stand point should I stay with the Adcom or go back to the Monster. I have heard it said the Adcom does not do much?? Thanks