Power Amp for Roksan Caspian system

I may be caught up in an add-on fever, at the moment, but I am looking at adding a power amp to my in-transiton system. So far, it consists of a Roksan Caspian 70-watt Integrated Amp and the solid Roksan Caspian CDP. I am thinking of an amp with some muscle, 125, 150, 200 watts - something which will team well with the Roksan integrated as a pre-amp or will match up to bi-amp (is this a good idea or even possible to bi-amp with different make amps?).. I have detoured onto this path during my search for speakers(!) I am looking to strongly power the speakers-to-be-named-later, most likely stand-mount monitors. $500/$600 or under for a used amp. Any thoughts? If you have any speaker ideas, $1500 or less, please feel free. I love listening to music as I roam the house, feel it more than study it. Thanks for any and all considerations.