Quality system, make poor recordings sound better?

Digital complicates things a lot in that there are unlimited ways any particular digital audio files may have been processed at various points in ways that have major effects on sound quality. The differences will no doubt be subtler
played on lesser equipment but more significant as the playback system gets better.

For example, there is much less difference between my best digital files and my worst(all lossless FLAC, a few converted from lossy compressed mp3 file download) played back on my Sangean WR-1 table radio, my least hifi playback device, though no slouch as table radios go, compared to played back at home via my main rig laying on teh big OHM F5 speakers. I have a half dozen or so other options in place for playing back those files concurrently. The others all fall in the middle somewhere in regards to overall sound quality.

the recordings must have sounded good to someones ears . more than one set of ears will hear a recording before it is pressed . how does a poor recording get let by ? cheap radio shack equipment in a major studio ?

question 1 = yes.
question 2 = variation of power from the wall, thus = yes

A good system should clearly highlight the differences in recording quality, but it shouldn't make a significant number of record sound so bad as not to be listenable. It would be kind of a foolish hobby to end up with an expensive system that makes the majority of your record collection sound bad.

Throughout the day your body is in a constant state of flux and it effects your ability to hear.

Radio Shack mixers in "good" studios? Please.