S002, welcome. The people that you heard that from have no clue, either as to Axioms or receivers. Axioms are smooth and accurate, as are any competently designed receivers(the receiver will amplify transparently and wouldn't add any sound characteristic of its own), so neither will be "bright" unless the program material being played has that characteristic on its own. Both the 2600 and 3806 are excellent and would of course do well with Axioms.

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Enjoy the music, not the equipment.