Do I need a 20 amp or 15 amp power conditioner/surge protector

I have a Dan D'Agostino Progression Stereo amp that has a 3,000 VA power supply transformer coupled to 400,000 microfarads of power supply storage capacitance.  It's a true triple down amp rated at 300 Watts into 8 Ohms, 600 Watts into 4 Ohms, and 1200 watts into 2 Ohms. I'm using a pair of Magnepan 3.7i's which are rated at 4 Ohms. 

One of the odd things is that the amp comes with 20 amp power cord that has a 20-amp IEC connector at the amplifier end and a three-conductor 15 amp AC plug at the other end. The instruction manual tells you to plug it into a 15 amp wall receptacle. 

After a recent scare, I decided I should get some protection as well as clean up the AC being fed to my components. My LAD explained to me that the minimum I should get is the Niagara 5000 because it's rate for 20 amps, but when I asked why does my amp need that when it's plugged into a 15 amp receptacle, he said that at high loads, the amp may be pulling a little more than 15 amps and power conditioner rated at 15 amps would restrict that and the audio quality would suffer. 

So, here I am trying to figure this out, I mean, my LAD may have point since the amp manufacturer supplies a 20 amp cord, but tells you to plug it into a 15 amp receptacle, but I just don't know. For the price point I'm looking at, I've narrowed it down to either the Furman ELITE20 (20 amp) or AudioQuest Niagara 1200 (15 amp). Do I really need a power conditioner rated at 20 amps, or will one rated at 15 amps be fine? Also, is it really possible under heavy load my amp could actually pull more than 15 amps out of a 15 amp receptacle? Very confusing... Thanks for any clarity you can provide. -cheers!




You are never going to use 15 amps.

Get a whole house surge protector as well. $75 to $300 dollars if you don’t already, but don’t rely on it alone.

Yes, you should use surge suppression devices at the outlet but when you are considering those look for certification to UL 1449. I don’t trust any power protection device, no matter how expensive, without it.

Personally I use Furman.

The homes in US have outlet voltages around 120V. A 15 amp circuit is rated to handle 15A*120V = 1800 watts. Your Progression amp is rated to output maximum of 1400 watts in 2 ohms load or 750W in 4 ohms load. So your 15A circuit is more than adequate to handle the Progression amp. What about your rest of the system? How much current rest of the components in your system rated to draw?

A power conditioner rated for 15A is all you need, just make your that you’re not overloading your 15A circuit.

Thanks all for your great info...very informative and helpful  -cheers

(I think the LAD just wanted to make a quick profit by selling me a $6000 power conditioner. My salesman always has been stellar for all the music gear I've bought over the years, but when it comes to accessories like cables, outlets, power, etc., I think he's less upfront - but hey, I get it - accessories are where they make their largest profit margins and he has to eat too. But in my gut I knew there was something fishy about what he said, that's why I asked for second opinions here 😀)

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ZeroSurge 2R20 for the best protection.

+1 on the big power flow to small amps.

Spend twice as much as a tiny tpa3116d2 for a 5 amp LPS and see.


@carlsbad -thanks. So north of you up here in the PNW, we rarely see thunder storms or hear lightning (even with all that rain...) but we get wind storms and that's when we loose power for a few seconds, and every time the power goes out, it trips the circuit breaker in the amp. I've been told every time the varistor does that, it looses some of it's ability to protect the next time until it doesn't have any "saves" left, then my amp will unprotected. I run like a mad man unplugging my audio gear when the wind strikes, but sometimes I'm just not fast enough, and often it's the wind that hits the power/transfer station first before it gets to my neighbor hood. So, that's why I need some sort of protection. Unfortunately, my power amp weights 125 pounds and costs 5 figures, so don't want to fry it for all of the above 😬 But, yes, otherwise, I would love to be able to keep it plugged into the wall... -cheers

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@carlsbad -thanks, good info to know. If I followed correctly, I think you're right regarding how my map operates. From the manual it says that when you plug it into the wall, then flip the big circuit breaker on/off switch in the back to the On position, the amp is then in standby mode. Then, to turn it on, there a soft switch (feels like a loose aluminum billet about a 1/4" round - you can jiggle it a little) hidden under a overhang on the front that you push up on and the following happens: you hear a "click" then about 7 - 10 seconds later, you hear a loud, but muffled, "pop". So, I believe that's the soft relay start you were referring to. When the power goes out, even if I unplug it from the wall, the big switch in the back trips and moves itself down into the Off position. The scary thing is, this once happened while I was listening to music and as soon as I heard it trip, I looked over at the amp and the power meter needles had shot up to the max of their range and slowly floated back down to zero... That event alone made me check my pants when I flew off the sofa.

Then, the scary event I alluded to in my original post, was after using the system this past Sat. night for watching a movie, afterwards, when the movie was over and the entire system was at idle (and no weather events - no wind, etc.) , my wife and I were talking and we heard a loud pop/bang and the smell of electrical ozone in the air, but nothing tripped or turned off - I went over to smell the vents of the Dan, McInstosh, and plasma TV but there was no electrical ozone nor arcing smell. The biggest problem is that I don't know the source of the bang, it was definitely one of those three components because that's the only thing on that side of the room. I also tested all my gear and everything operates and sounds as normal.

Everyone in another thread told me it was most likely the varistor (MOV) that blew in the Dan, but left the circuit open and so it still works, but now I have no surge protection. So, I slid the top off of the Dan and saw absolute nothing (to the naked eye and bright lights) - no swelling or burnt caps, resistors, transistors, and more to the point, the disc MOV is very easy to see because it goes across both terminals of the input mains - it still looks shiny new - no carbon soot, no discoloration, no smells, etc. My LAD salesman told me that when Dan's go, which isn't often, they just stop working altogether, etc.; that's when he suggested I buy the Niagara 5000, so that's what started me on this quest to figure out the best protection at the best price that wouldn't degrade the sound... -cheers

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+1 for a whole house surge protector. @erik_squires.

Though the AQ Niagra 7000 shouldn't limit power transients demands, I would still plug an amp directly to the wall.- That is if you have a whole house surge protector at the main box.



Whole house protectors have a relatively high clamping voltage. They will prevent your house from burning down, and protect your air conditioner and oven but living in South Carolina I would not plug anything delicate into the wall without one.

I will say that last serious thunderstorm I lost my MacBook Air. I forgot about it and left it plugged straight into the wall. Everything I have on a surge protector was fine.


3,000 VA power supply transformer coupled to 400,000 microfarads of power supply storage capacitance.

3000 VA / 120V = 25 amps...


Are AC line-treatment devices necessary? Define necessary. "We try to build equipment that puts up with dirty AC lines," Pass told me. "Our customers expect it, and if they have a problem, we hear about it. We don’t design around the assumption that there is AC line conditioning in the system. That said, if the line conditioning has adequate current capacity, we expect some benefit."

That’s a big "if," since some types of line conditioner can choke off current and squash dynamics.

Power According to Pass |


Bigger is better...



Though the AQ Niagra 7000 shouldn’t limit power transients demands, I would still plug an amp directly to the wall.

       I agree!

@jea48 Thanks for the info and video - very informative and revelatory to learn that the spike increases the further away from the panel. But mostly thanks for the formula:  3000 VA / 120V = 25 amp. So, now I kinda see why my LAD said I should at least get the 20 amp rated Niagara 5000, but of course the question is, in practically, even in loud passages, especially with lots of bass, occasionally my meter needles will go up to 400 watts at the most. So, even though my Dan is capable of 25 amps, I'm most likely not pulling anywhere close to that I would think. (Unless transients can suck higher than 15 amps without the watt meters reflecting those spikes because they're too fast for them to react to?) -cheers

“Unless transients can suck higher than 15 amps without the watt meters reflecting those spikes because they’re too fast for them to react to?”

In that case, you breaker should trip :-) In all reality the capacitors inside your amplifier stores enough electrical charge in the form of an electrostatic field between its conductors to handle any peaks or spikes. 

Can someone please tell me how a 20amp rated Niagara 5000 is beneficial on a 15A circuit? I can see inserting a 15A rated conditioner on a 20A circuit as bottleneck for an amp connected through that very conditioner.

@lalitk -thanks Yes, I see what you're saying and was thinking the same thing, it logically isn't adding up, especially when the Dan's manual says "plug into a 15 amp receptacle", yet, they provide a 12 gauge 20 amp cord with a 15 amp male plug for the wall end...? I see now why this hobby can stretch out into the twilight zone... It's situations like this where there is seemingly contradictions all over the place, in this case, starting with the manufacturers owner's manual and supplied cord, then all the cross talk from LAD's and hobbyist alike... 🤪 But that's nothing new... We have on one side of the aisle pure science that just looks at the numbers and the physics behind those numbers; on the other side, we have those that say the numbers don't tell the whole story... -cheers

As per jea’s calculation, you really need a 30A circuit to run Progression amp without limiting its peaks.

I concur!

IMO: The Progression amp should have a 250 volt 20 amp dedicated circuit. That will give you 5000 watts.

@jimmy_jet said:

I see what you’re saying and was thinking the same thing, it logically isn’t adding up, especially when the Dan’s manual says "plug into a 15 amp receptacle", yet, they provide a 12 gauge 20 amp cord with a 15 amp male plug for the wall end...?


How many Dan D’Agostino Progression Stereo amps would Dan sell if the cord had a 20 amp male plug? Most of the wall outlets in our homes are 15 amp. (In wall branch circuit wiring is 14 gauge copper connected to a 15 amp breaker.) Good thing Dan spent the money for a soft start circuit on the amp.

(Note: Two or more 15 amp receptacles can be installed on a 20 amp branch circuit per electrical code. A duplex is two.receptacles)

The amp probably sounds ’fine’ on a 15 amp circuit fed with #14 gauge copper wire. It more than likely would sound even better on a 15 amp dedicated circuit fed using #12 copper wire. Or even a 15 amp dedicated circuit fed using #10 solid copper wire.

The wall outlet could still be a 15 amp duplex receptacle outlet per electrical code. If you wanted to use a 20 amp duplex receptacle outlet then the circuit breaker would need to be a 20 amp to meet electrical code. You can still use the same power cord with the 15 amp male plug. The only difference between the 15A and 20A plug is the neutral blade on the 20 amp plug is turned 90 degrees with repect to the Hot blade...

FWIW a 15 amp circuit breaker will pass short quick current draws of 30 amps all day long without the breaker tripping. It will handle a continuous connected load of 15 amps without tripping.


Pass said:

"choke off current and squash dynamics."

It’s not a continuous draw of current Pass is talking about. 14 gauge wire is more than big enough for the continuous current draw of Dan’s amplifier. Using a bigger wire gauge is for dynamics.

3,000 VA power supply transformer

Fed with #14 gauge copper wire...

Any other loads on the 15 amp circuit? Any idea the total length of the #14 gauge branch circuit wiring from the electrical panel to the wall outlet the amp is plugged into? The length of the wiring can make a difference too.


@jea48 -thanks. Regarding:

FWIW a 15 amp circuit breaker will pass short quick current draws of 30 amps all day long without the breaker tripping

I think that's what my LAD was alluding to when he said the amp would sound better with the Niagara 5000 because it's rated at 20 amps - because transients are capable of pulling more than 15 amps from a 15 amp circuit as you explained. It's starting to make sense now. I still think the Niagara's are overkill for my purposes and I don't "think" I need a line conditioner because my system is silent at idle - all I'm really looking for is a surge protector/voltage stabilizer that will protect my power amp and not degrade it's current sound/performance. As for the rest of the gear on my media room circuit, it's all pretty low-level stuff like turntable, SACD, Blu-ray, network transport, and pre-amp. -cheers


I think you missed the point I was trying to make. JMHO, a 15A branch circuit, which I assume is a convenience outlet branch circuit consisting of 14 gauge copper wire, is not doing the Dan D’Agostino Progression Stereo amp justice.

If it were me I would have a 20 amp dedicated branch circuit installed. Circuit minimum wire size for a 20 amp circuit is #12awg copper. If it were me I would pay the extra cost and have #10awg solid copper installed.

Type of branch circuit wiring to have installed?

Read pages 16 thru 36.







This just came to mind

The 240V Option

Some high end amps can be switched over and run on 220 volts and I recommend it may sound better. The transformer primaries and the core seem to run slight more efficiently yielding lower impedance so the supply might appear slightly ‘stiffer’ to the amp’s audio circuits (always a good thing). Because the amp is now running at twice the voltage but half the amps (current) the wall wiring looks twice as thick to the amp as it does at 120 volt (ohms law). Now the amp makes even less audio noise on the line and it then rejects its own line noise better. The 220 volt outlet can be a standard 15 amp with 10 Ga.. Wire up to 80 feet then 8 gauge beyond that.

For the 220 volt lines, the electrician may, or may not know about a NEMA receptacle and plug number that is the same size and form as our common Edison duplex 120 volt receptacle but the wide blade of the plug is on the opposite side as the 120 volt duplex. Hubble or commercial Leviton works fine for 220 volt, and the 6-20 series looks less industrial in your home.

It is Nema plug number 6-20P. ‘Stay on line‘ is a good source but your electrician may like a local supplier.


Last Trick – Twist the conductors

Lastly, you might ask him to twist the conductors one twist every 6-8 inches or so. Each line should be alternately twisted relative to the one next to it. This prevents any coherent coupling between them. Keep them away from each other by minimum 4 inches. It is perfectly OK to cross them at a right angle.

Final Word

If your electrician has any concerns about all this, be aware he is always concerned about CONTINUOUS current draw and rates everything and splits up the loads like the air conditioning and the electric dryer for the available amperage. Please explain to him that we are designing for incredibly short peak current pulses and we need the resistance back to the utility as low as possible for best amplifier performance. The continuous draw is negligible from an electrical standpoint. 10 gauge wire is the largest size that will fit into a wall outlet and as far as I know does not violate any codes but you and your electrician are responsible to be sure this is true in your state, county, and city.

Be sure that your speaker cable is at least 10 gauge. You should consider 8 or 9 gauge for speakers that are below 87db sensitivity, and/ or 4 ohms. Some manufacturers say, ‘our 14 gauge behaves like 10 gauge, etc.’, this could be true but I go for the real measured gauge.

Now, without exception over the last 12 years, comments from those that have done the above heavy gauge wire wall power mods say there is audible improvement in dynamics while making the sound even more detailed, yet much more relaxed with dark backgrounds leaving only the notes and music. I was very surprised the first time I did this house power mod. I did not expect the mid-range and the highs to clean up and get more coherent as much as they did. Of course bass and dynamics are better as you would expect with better current delivery.


link to page:




© 2022 · MSB Technology Corp.

@ditusa @jea48 -thanks gents for all the great info and interesting articles - definitely something to consider down the road. And indeed, the top of the line D'Agostinos actually require a minimum of 220v/20amp power source, so those folks who purchase his six-figure power amps have to get the electrical work done first (not a problem I'll ever have (unless I win the lottery)). I think the furtherest I may go is having the 20amp circuit installed. -cheers

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@ditusa I’m joining the 220V crowd. I just ordered a 220V amp today. By the time it gets here (from Europe) I’ll have my 220V circuit modified and ready to power it up. Second: who is this msbtechnology that wrote up the paper you referenced. I like it a lot. If you go to the home page, they are a CNC shop so I’m guessing the owner is an audiophile.


They manufacturer audio equipment. See link below.