what kind of power conditioner for front end?

for many years, I used an isolation transformer, plugged into another large isolation transformer, both Soundtrappers, for all my front-end equipment.  That was Stereophiles top recommendation c. 1985, but many power conditioners have come to market since then, many of which are considered very good.  Got rid of the large iso, it hummed too much to tolerate in the same room with the audio equipment.  Amp clearly sounds best plugged into the wall with a good cord. 

I tried a ZeroSurge (which is, I believe, non-destructive, and it shouldn't have limited power, but would protect the equipment from surges), but when I play records, it caused the light above the turntable (plugged into the ZS) to dim and flicker.  The power draw from the phono stage (a Rogers PA-2) somehow affected the other outlets. I'm not sure why, but if the power to the phono pre is sagging through the ZS, that's not good. 

Plugged everything bck into the not-so-large isolation transformer, turntable light remains steady,  Seems to reduce noise.  Plugged everything into an unfiltered power bar (a PS Audio), no light flickering.  It seemed to have clearer and lower bass, possibly not quite as clear and quiet in the top end.  But that is effectively like plugging things into the wall, so there's no protection at all. 

So I'm puzzled. Does "everyone" use some power conditioning on the front-end equipment?  Is there a type of conditioner that is better than others?  How do you know what size conditioner you will need?  I do not want something that hums or makes noise of its own (I understand an AQ Niagra would) - noise is what I'm trying to eliminate, along with some surge protection.   I won't spend $10k unless I heard one that knocked me flat, which seems unlikely. I've never tried a regenerator.