Sonic differences feeding a P20 from a 15A circuit versus a 20A circuit

I am posting this for a friend who’s been very busy recently… he works at a company making equipment key to keeping seriously ill Covid-19 patients alive. So as you can imagine they have a lot of orders and he is working about as much as he can.

He had recently purchased a P20 based on my recommendations and experiences with P300s, P10s, and currently 2 P15s in my setups.

His main power consumers are a pair of PASS AX160.5 Monoblock Class A amplifiers which feed a pair of B&W 802 D2 speakers. His digital source is similar to one of mine, a DIY dual-mono ES9038Q2M DAC card on a FiFoPi I2S reclocker fed from an RPi 3 and outputting through a pair of transformers sourced from Kazakhstan. The amps run at nearly 5A each, so he has a constant 9.8A load on the P20, just below the max output for the unit fed from a 15A line.

Previously he powered his system via a 5KVA balanced AC transformer.

After only a couple of days with the P20 he reported:

“More natural sounding music overall. Wider, deeper, and more enveloping sound stage. Greater resolution of low level sounds providing new details. Much more solid, deeper, and cleaner bass. More delicate highs… female vocal sounds nicer than before. Quieter backgrounds.”

Pretty much just as I expected.

His only question was whether the 3D image with the transformer seemed larger.

This was using the 15A AC into the P20. As his amps nearly max out the P20 in this configuration, I suggested he try powering it from a 20A service.

After arranging to have a 20A service installed, he tried his setup using the 20A input of the P20.

On the good side, his output loads reduced to 65% using the Sine-Wave output and 52% with Multi-Wave. BUT, after a couple of days of run-time on this configuration, he did not feel the sonics were quite as good in this configuration as they were using the 15A input. He reported that the overall sonics were a bit less vivid and less delicate.

After a bit more break-in he commented ” it’s just like two pieces of same nice steak, cooked by different chefs, the 15A is juicier.”

His two AC circuits are fairly similar:

15A circuit: Square D 15A breaker -> unknown wire -> 15A/20A duplex outlet -> stock PS power cord -> P20 15A inlet

20A circuit: Square D 20A breaker -> unknown wire -> 15A/20A duplex outlet -> 3ft NEMA 5-20P to IEC C19 Power Cable 12AWG SJT -> P20 20A inlet

My advice so far has been to give the 20A setup more break-in time while looking for upgrades to his 20A power cord and 15A/20A receptacle.

Can any other P20 users report on differences they’ve heard between using the unit’s 15A input versus the 20A input, with similar 15A and 20A AC circuit paths?

AND can PS Audio provide some details of how the internal AC paths and circuitry differ between these two AC inputs? I told him I thought probably very little… maybe the surge protection and AC input filtration along with a sensor to tell the control system which AC power source is being used. BUT it could be much more complex than that AND impact the output results more.

Thanks for answers in advance!

Greg in Mississippi

I started using my P20 in 15 amp mode before I knew that the circuit it was plugged into was on a 20 amp breaker. I switched to 20 Amps and honestly don’t recall hearing any difference.

I wrote it off as the 20Amps are not really needed unless I’m really stressing the P20. I am not stressing it by any stretch of the imagination as I have never seen my power consumption exceed 700 Watts.

You simply won’t believe or understand what a change a ridiculously expensive power cable can make with the P20. I use a Shunyata Sigma NR which seems like madness until you hear it. With the cables he is using it’s pretty much a why bother affair. Sad but true. No, it doesn’t make any sense. But listen to it then speak.

using a “cheater” of any type is not only not legal it renders your insurance void! If you rent, can just go to prison then. Of course most likely no accident. However to the point, HUGE sonic difference! It is not even designed for that. IT is like putting 87 octane in a car that only takes 93 octane! This is not something subjective. You are abusing the machine.

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Please give it a rest, 2chan.

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In Maryland, it is not illegal to use cheaters. But they can not be purchased, as they were banned for sale years ago.

Thanks everyone for your replies.

AND my friend is not using any cheaters in his setup and I don’t see how that was implied in how I described it. If anyone has questions, please ask. Do understand that (for those who don’t personally have a P20) the P20 has 2 AC inputs, one for a 15A AC cord and one for a 20A AC cord, each with the appropriate IEC inlet, and with a sliding door that blocks the other when one is in use AND signals to the P20 firmware to use the appropriate max output for the input type.

Also, he is in Canada. I am not aware of what different regulations are in place for his AC setups. But as I mentioned, he IS an accomplished EE and aware of things such as this.

Greg in Mississippi

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I completely apologize. I just looked at mine. i was not even aware of this. mine were professionally installed so i had no idea. I just wanted everyone to be safe. I do not see how people can lift these anyhow but that is a different story :slight_smile:


The only thing I’d like to add is that with music it is about hitting the right balance. Here better, bigger, more pure, etc doesn’t always work. If we had a perfect amplifier with ideal components, it would probably sound awful. Music equipment is not instrumentation electronics, they measure to a certain point, after that only ears becomes the judges. Poor components can often give the taste to music. Perhaps his 15A outlet had a little bit more “give” or “sag” under load that softened the midrange to his liking. More 3D, in my mind, which I do prefer as well, is a range of frequencies somewhere in upper bass, lower-mid midrage region in audio spectrum. To get a little more of that, he can try a smaller gauge power cables. Solid core interconnects can do wonders here too (tv antenna cables for example). He needs a little bit more efficiency in the midrange or sag upper and/or lower ones.