I think it is time to step back and look at some of the statements made in this thread:
" it really boils down to the AVR's power supply in respect to being able to drive speakers to higher levels and being able to sustain it. "
True, to an extent. Higher power is better. But measure the difference not in watts, but db. A rule of thumb is 2X the power is 3 db and that is about the minimum it takes to hear a difference.
"a recipe for disaster as clipping can occur which often damages speakers."
Sort of. Running an amp into clipping creates square waves which contain harmonics that can overload and damage the tweeter, only. This can be an issue at a rock concert, not generally in a house with any reasonable amp where normal listening levels use very little power.
"As that Yamaha.... does not have a very large power supply" & " if power supply is not able to supply enough juice to the amps it does not matter what the specifications are in the manual."
Power supply capability can be inferred by the audio power output. See db, above. You will need to double the power to hear it. Power tests are regulated by the FTC.
http://www.ftc.gov/os/2010/01/P974222amplifierrule.pdf
" If two channels driven gives 140W/ch and 5 channels driven gives 80W/ch, then that is evidence of a less powerful power supply."
True. But remember that if one tests at 80 and the other at 100, the difference is not audible. There is also controversy as to running all channels flat out is a realistic test that relates anything to real world use.
"The issue with the manufacturers tests is that they never do full frequency tests they do it with a 1kHz test tone and thats how they get away with those over inflated readings."
Not true. The FTC ", requires a manufacturer’s stated power rating must be met, with both channels driven, over the advertised frequency range – usually 20 Hz to 20 kHz – at no more than the rated total harmonic distortion (or THD)."
"Various amplifier types like Class D will produce different tones."
No evidence to support this. The difference between amp design is efficiency.
Class AB amps are 30 to 50% efficient while class D amps are 80 to 90% efficient. AB amps run hotter, need bigger heat sinks and power supplies. While many claim sonic superiority of one vs the other, this has not been demonstrated in ABX blind testing, much to the frustration of "golden ears".
" Higher quality components like capacitors, transistors, resistors, transformers (major differences) , etc do cost more and are built with tighter tolerances. Lesser quality parts can interact and alter the integrity of an incoming signal. "
Generally quality of the part equates to reliability. Higher quality resistors are tighter tolerance (+/- ohms) and do not affect sound. Similar for transistors and caps. Building an amp out of military grade components will not sound better but might last longer and will be more expensive.
Remember that blind testing has been done to compare amps of different price / quality and no one could pick out the difference. This does not include features such as room equalization.
"A rule of thumb here is, generally a good quality 50watt amp will weigh much much more than a low quality 100watt amplifier."
It depends on design. A good quality class D amp with a toroidal transformer might weigh less but sound the same as a good quality class AB with a traditional transformer. Manufacturers know that people equate weight with quality and use that to sell their products.