What do you consider a low Watt amp ? One of the most transparent amps the Benchmark AHB2 running full power both channels driven has a SNR about 130dB. So you can play at 120dBSPL and your noise floor will be at -10dBSPL in other words silence. In bridged mode it can put out 500 watts @ 4 Ohm with .00026% distortion. At least with this amp any distortion you can hear comes from other sources.
will a lower SNR component mask high power amp distortion?No
it safe to say that the better the SNR of a preamp and source, the more you will hear the distortion from a higher powered amp?Yes