Marantz pm6006 upgrade?


I'm looking for a new amplifier, reason why i bought this marantz was the built-in dac but now i am considering an external dac + amplifier.

I am considering Exposure amps (1010 or 2010). Can you suggest any amps (im okay with used ones) better than this one under 750 dollars. 

My speakers are Cabasse antigua mc170, preferred music genres: jazz, alternative rock, pop



coz22
Thank you for valuable advice, lastly what DAC should i prefer to maintain the sound i have now
Any dac advices ?? I need a better one comparing to in-built dac in marantz pm6006
Schiit recently released the Modius dac for $200.  I've had a few of their dacs and they really make great sounding gear.  I've had the Modi 3, Modi Uber, Bifrost Multibit among others.  I'm waiting for my Modius to arrive.