SK, if you "keep reading" that Axioms and Pioneers are "bright", then you're reading sources which are misinformed or uninformed but continue to spread audio mythologies. Again, Axioms are accurate speakers which reproduce the characteristics of the source material, be it dull, bright, just right, or whatever.
Your Pioneer, along with all competently designed receivers has a flat 20-20KHz frequency response and there's no way that it can mysteriously add some sonic characteristic of its own which would require a substantial deviation from flat response over a wide band. This is what modern audio technology teaches us and claims to the contrary collapse when put to a carefully controlled blind test in which the ears alone have to actually be trusted.
As to scaling in a receiver, keep in mind that all HDTV sets have to scale incoming signals if they don't match the sets' native resolution. Scaling in a receiver or player would only be of advantage if it happened to do a visibly better job of it than the circuit in the set itself.
You have no reliable way to "test" those other receivers. You have excellent equipment; relax and enjoy.
