Charles, not only has this been a topic anewed every month, but also every year. The answer is always essentially the same and will continue to be the same unless there's some major new discovery(Nobel prize in physics class)in the relevant technology(truth has no expiration date). As to amplifiers, the relevant factors(again)are audibly flat frequency response with inaudibly low noise and distortion. If this is accomplished the result is transparent amplification with no added sonic characteristic. The editor of the Audio Critic summarises it quite well in "Electronic Signal Paths Do Not Have a Personality!" .

As to the DAC matter, it's also been pointed out, several times by Alan, that DACs are now a mature technology. Relatively small measurable differences in specs such as the SNR have no audible effect when the typical inexpensive DAC(available to manufacturers in quantity for less than $1 each, as you correctly point out)has a dynamic range more than sufficient for source material which almost never has a dynamic range of more than about 60dB and which has an inaudibly low noise floor.

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Enjoy the music, not the equipment.