To clarify my opinion (since my statement on the Onkyo vs. Technics was related to an age difference as the only affecting parameter) even new equipment from separate brands can be compared and differentiated by ear. Not all the blind tests that are performed result in 100% of people incapable of distinguishing differences between equipment.
Take for example 2 cd players, both brand new, one sporting a 192khz Motorola DAC and the other with a Sony 96khz DAC and do the blind test. Then sample a group of people listening to the Denon 4802 and an Onkyo 797.
I would wager that a larger proportion of listeners would distinguish the 2 cd players but not the receivers.
We simply cannot deny that changing the equipment could make a difference, however that change may not necessarily be an 'upgrade'.
