AMD,
I echo JohnK's opinion.
With the equipment you are looking at, it is unlikely you would hear any significant difference between those receivers.
Differences between speakers is usually apparent to almost anyone. However, differences between electronics so close in design will not likely be distinguishable by the usual home users (if at all) unless you were using some very high tech measuring equipment.
If you want some warm and sludgy sounding music, buy some Bose speakers instead of the Axioms. The speaker change will produce a far different 'musical' sound than swapping between any of those 3 receivers you mentioned.
