Parasound A21 is a great 2 channel amp depending on your room size speaker and listening volume it might be just fine. Now if you want to drive your speakers at louder volume JC1 will be your better choice. The JC1 is in my opinion more muscle and more musical and you will most definitely hear a bump in Bass. The sound signature is John Curl no doubt but more of it with it operating in class A up to the 1st. 25 watts.
I have not had the opportunity to play with the JC5 so I cant really comment.
As far as the the A21 VS Anthem both are great at that price point, my experience was with the Anthem 225 integrated which is an awesome combo similar from a price power prospective but the Anthem comes with the built in pre which by the way is better than the Parasound proposition.
Enjoy