Why does better power = better sound?

I'll share a few anecdotes based on my experience in my system, for what they are worth:
first, I use very efficient horn speakers and it took some doing to get the line quiet. Not 60 hz hum exactly, but you could hear a sort of hash that was reduced through various power conditioners and grounding arrangements. I've been able to get this sorted without the need for power conditioning, but I'm sensitive to this. Does it raise the 'noise floor' or make music sound less clear and distinct coming through the system? I think so.
second, I've been experimenting with various rectifiers in the power supply of my phono stage. In exploring issues like voltage drop or 'tube sag,' (something I know guitarists talk about when they want to get a certain 'crunch' or distortion out of an amp), it seems like the tube that sounds better has less 'sag' ; this contributes to distortion. Conversely, the more robust rectifier sounds more effortless, although there may be trade offs elsewhere in the sound spectrum.
I just changed to a battery line stage. For some reason, there was a low level sizzle, which didn't make much sense. It went away after a large crew, with two bucket trucks, went to work on a transformer one up from mine on the line.
I'm looking forward to seeing how the big Equi=Tech wall panel works in my next room, for precisely the reason that AC power seems to determine a lot about how my system sounds.

I would be VERY curious to see the DC line voltage monitored with a differential scope that records the AC leakage of any sort (anything that is not DC) and see what it tells you all.

DC is DC, and what you think is coming in is 100% immaterial till you show it out the DC side of the supply. An HP differntial voltage meter is thousands of times more sensitive than the human ear. If your DC signal has noise in it, what is it and what magnitude? I really can't see where a 0 dB offset average over time is going to be "heard". This test measures anything that isn't pure DC to the set reference value (sag, spikes, ripple...you name it) and records it.

Most wall to electronics issues are crappy plugs that change contact resistance with heat due to poor contact pressure. All those expensive cords fix that, but what's in the middle is what people think they get! No, it's usually the plugs. An IEC plug is not even an 100% usable interface distance. The plug makes make spec "contact" till about two-third of the way in. A good hospital grade plug has spec contact pressure almost immediately. Go play around with them and see. My IEC plugs work loose on my equipment all the time. The hospital grade wall plug? Never.

Romex right from the wall to the transformer with twist lock caps? Way better than a poor retention IEC plug (I HATE those plugs!). A hospital grade wall outlet and plug on the back of your amp would be about three times the retention force of an IEC plug / socket. The continuity is all about the contact pressure with temporary sockets.

There are several essays or presentations on this Jim Brown website that apply to interference and chokes. recommended reading.

http://www.audiosystemsgroup.com/publish.htm

I've put in 5 direct lines with 10 gauge romex and upgraded receptacles. The difference is amazing. I would like to the take the next step forward and was looking for recommendations. I have tried a couple of power conditioners, but for whatever positive affect they had, they also had drawbacks - less dynamics or a veil around the music. Great thread.

I am still waiting for the WA chips to arrive, 4 fuse, 2 transformer and one tonearm chip.

I'll post my impressions later.

What I can say is that anyone looking for a replacement receptacle,should try the Furutech GTX D - gold.

I have used several hospital Hubbels,an FIM, and Shunyata ZR1,and so far the Furutech is the one that tops them all.
I'm told it gets better with continued usuage.

I once owned a Sunfire true subwoofer, that despite it's dancing across the floor, did add extra bottom end slam to my CLS's when I had them.

What I didn't like was the edginess that I seemed to get thru my system when I used the Sunfire.

I have a few electrical engineer friends, and one brought over a quality Fluke and we measured the power on the line with the sub in and out of the system.

With the sub in, the chart was very ragged, clearly the sub was spewing all kinds of hash and noisey distortions back into the line, which the other components were being affected by.I am not saying the Sunfire was a flawed product it did what it was supoosed to do, but at a cost.It added more than just bass.

At that time I wasn't using dedicated lines,nor any power conditioning as I felt like others, that it was a waste of money.

The absence of distortions on the print out when the sub was unplugged and out of the system was a deal changer for me.

Further proof that bad power can equal bad sound, and that even some components are the culprits, never mind your neighbour with the basement full of electrical motor powered wood working tools.