Amp to PowerPlant or directly to wall?

I vote wall.

With local incoming THD ranges between 3.5%-5.5% (P20’s outgoing 0.2%-0.3%), Pass-Labs XA160.8 mono blocks sound significantly better when connected to the P20 rather than directly to the wall. This is consistent, even when compared to each mono block being plugged directly to its own dedicated 20A wall-socket.

As a further context, the P20 is connected to the 20A socket with AQ FireBird, and all remaining components are fed through AQ Hurricane.


Are you stating this as scientifically proven or is it your observation only? Do you feel confident that Pass-Labs was unable to build an amplifier that can deal with ordinary power? That would be a mean-spirited belief.

How were amplifiers even sold before the P20?

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Thanks to all who replied. Three takeaways:

  1. I’m not crazy when I hear better SQ directly from the wall, since this happens for some other people also.
  2. Most people who prefer the sound with the amp plugged in to a regenerator have a P15 or P20. As I said in my original post, the P12 ought to have more than enough power for my needs. But maybe a P15 would be better for reasons that are unclear.
  3. After a few days of listening direct from the wall, I still prefer it this way; so I’ll leave things as they are and see what develops over time. Maybe get that outlet behind the amp put on a dedicated line.

If anyone else wants to add their experience, please do so!

Go with what sounds best to YOUR ears in your system No cost in experimenting with your configuration.


One of my 600s was very noisy when it was plugged into the P20. Changed tubes. Nope. Changed power cord. Nope. Changed speaker wire. Nope. Plugged into wall. Ta-da! Don’t get it.


I would think incoming noise measured on the line would be a significant variable for everyone. I only have 1% inbound distortion on my lines. Some people have way more. I’m in the wall.

1% is one of the lowest incoming THD I have seen reported.

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I know. I’m not sure the reason. Newer sub division? Under ground wires? New runs of wire in the room w limited plugs? Nothing special. That’s for sure

Probably just luck, but it is certainly nice.

On the opposite side of the spectrum, my THD as measured from the P20, runs between 9 and 10% on average. Occasionally a bit higher, or a bit lower. In-coming voltage is considerably better, and stays within a volt of 120. The THD output of the P20 is constant at .1%. So, regardless of crappy incoming distortion, the measured output is great. I don’t know whether calming these nastiest results in better sound, but things do sound better when all my stuff are plugged into it, even amps.


Recently, Com Ed changed out the transformer and feed from the pole to my house. Only a slight change in distortion as shown on the P20. Other issues are afoot.


0.9% incoming


“Lucky” (I thought in my best Napoleon Dynamite inner voice).


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Huge! You are lucky indeed! Always had 2-2.2 THD here.

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Congrats on being King of Low Distortion. I will remain the Court Jester.


Took a quick peek at the P10 screen this morning…6+% THD inbound!

Worst I have ever noted, but I attribute this to the storms that have moved (and are moving through) the area.

Typically, the P10 indicates inbound THD at less than 2%.


5.7% in
0.1% out
116V in
120.2 V out
P20 seems and sounds like it’s doing it’s job.

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Wow. My distortion is between 1.5 and 2.1 percent, varying, haven’t found rhyme or reason. 0.1 percent out. Using less than 20 percent when fully loaded. Sound is so good. Even with low incoming distortion, so beats the wall.

And then I waste it with tubes in both pre and power amps, :wink: