Apollon audio vs Nord Hypex NC500 mono blocks which to pick

Colin at Nord has been at it a whole lot longer and is easy to communicate with.  Unless you just want monoblocks for some reason all you are getting is higher cost and a second case.  I have had both stereo and mono Nord's in house at the same time and no sound difference.  There was a company in the US making them but they were just using off the shelf parts any DIY could buy. 

Money as the 500 modules were twice as expensive.  Merrill Audio used to sell a stereo version but it didn't sell.  Colin at Nord got into it as a sideline to his speaker business and then the publicity he got from us on the AudioShark forum made his amp business take off.  The guys at Apollon came later and piggy backed on Colin's model. 

Or one stereo and one mono depending on where you were planning on placing them and the width of your shelf.  The width of the faceplate on the standard Nord case is 13 3/8".  The 3 channel is the best choice price wise.  As the whole amp is modular it is easy to work on. 

There is a review of the Nord NC500 amp on 6 Moons.  If I remember correctly the Merrill amp was called the Taranis and also reviewed.  Also the Acoustic Imagery Atsah 500.  Reviews are out there you just have to look.  You are getting far to hung up on paper specs.  I have used amps with all of the "major" Class D techs with speakers that were more difficult to drive than the top half of the Aries and they all work fine.  The thing is they all sound different with different speakers.