Apollon 1ET6525SA ST Amplifier Review

[Matias]

I plugged a consumption meter onto the power cord. This amp, my unit, consumes about 16.5 W when idle. It needs to get very loud, hearing damage levels of loud before the base consumption is exceeded with my subwoofers. For comparison I measured 28.6 Watts from two NC400 mono blocks.

But then you are comparing 2 modules + 1 PS against 2 modules + 2 PS, it is not the same.

The modules themselves have idle power rated Purifi 2 x 1.6W versus Hypex 2 x 5.3W, so the difference is 7.4W between similar amps. A light bulb. Is this the main difference to choose one over the other? I am curious.

 

[Sokel]

But then you are comparing 2 modules + 1 PS against 2 modules + 2 PS, it is not the same.

The modules themselves have idle power rated Purifi 2 x 1.6W versus Hypex 2 x 5.3W, so the difference is 7,4W between similar amps. A light bulb. Is this the main difference to choose one over the other? I am curious.

That's the base amp consumption, any buffer or add-on board must be added along with the PSU.

 

[Matias]

Which is the same for both amps. Again consider same number of PS, same add-on board, only the modules different. Why choose one over the other? Power consumption in idle only?

 

[Luvchampagne]

I plugged a consumption meter onto the power cord. This amp, my unit, consumes about 16.5 W when idle. It needs to get very loud, hearing damage levels of loud before the base consumption is exceeded with my subwoofers. For comparison I measured 28.6 Watts from two NC400 mono blocks.

Leaving your 16.5 W amplifier on 24/7 in Finland costs approximately
€1.05 to €1.40 less per month than leaving the two
28.6 W NC400 mono blocks
on.
The calculation is based on the following breakdown:

1. Energy Consumption Comparison (Monthly)

• Your Amplifier (16.5 W):
  • Daily:
    
    
    
    16.5W×24hours=396Wh (0.396 kWh)
  • Monthly (30 days):
    
    
    
    0.396kWh×30=11.88kWh
• NC400 Mono Blocks
  (28.6 W):
  • Daily:
    
    
    
    28.6W×24hours=686.4Wh (0.686 kWh)
  • Monthly (30 days):
    
    
    
    0.686kWh×30=20.58kWh
• Difference:
  
  
  
  8.7kWh
  per month.

2. Estimated Cost in Finland
Electricity prices in Finland fluctuate, but for 2025–2026, a typical total price for household consumers (including energy, transmission, and taxes) is roughly 12 to 16 euro cents per kWh.

Statista +1

• At 12 c/kWh:
  
  
  
  8.7kWh×0.12=€1.04
  saved per month.
• At 16 c/kWh:
  
  
  
  8.7kWh×0.16=€1.39
  saved per month.

3. Yearly Impact
If left on continuously, switching to the 16.5 W idle unit saves you roughly €12.50 to €16.70 per year.

 

[Matias]

...or just switch them off when not in use. Save money and protect them from possible power surges that may damage the PS.

 

[amper42]

But then you are comparing 2 modules + 1 PS against 2 modules + 2 PS, it is not the same.

The modules themselves have idle power rated Purifi 2 x 1.6W versus Hypex 2 x 5.3W, so the difference is 7,4W between similar amps. A light bulb. Is this the main difference to choose one over the other? I am curious.

In most cases, a single PS is more than enough. Going with a separate PS per channel is usually over kill. The Purifi amp sips power. It has the best efficiency I have measured. Even at loud levels a stereo Purifi amp will usually use less than 17W when measured with Kill-a-watt. Compare that to my Monolith X7 that can reach 150W while idle and over 200W at the same audio levels.

 

[Sokel]

Which is the same for both amps. Again consider same number os PS, same add-on board, only the modules different. Why choose one over the other? Power consumption in idle only?

For me, personally?
Proven lower impedance driving ability, nicer build, components and absence of failing reports (as a company, that's almost a tradition for Purifi)

 

[haris525]

I am curious, what made you 2 order this Apollon amp with the Purifi 1ET6525SA instead of the Hypex NCx500?

good point, I was going to order the NCx500, but I wanted sota performance, and noticed that 6525SA has lower distortion above 1khz frequencies. I am sure they are very likely inaudible for both amps. I am eventually planning to buy the 9040BA Dual mono, so wanted to see how the lower level purifi 6525SA performs.

 

[Matias]

For me, personally?
Proven lower impedance driving ability, nicer build, components and absence of failing reports (as a company, that's almost a tradition for Purifi)

From what I can see in pictures, both the NCx500 and 1ET6525SA use Wima and Rubycon caps, so similar build quality.

As to driving lower impedance, they are rated into 2 ohms NCx500 700W versus 510W 1ET6525SA. Or 28A versus ~25A peak current.

good point, I was going to order the NCx500, but I wanted sota performance, and noticed that 6525SA has lower distortion above 1khz frequencies. I am sure they are very likely inaudible for both amps. I am eventually planning to buy the 9040BA Dual mono, so wanted to see how the lower level purifi 6525SA performs.

For high frequency distortion Bruno P recommends this test which Amir did below.

 

[haris525]

From what I can see in pictures, both the NCx500 and 1ET6525SA use Wima and Rubycon caps, so similar build quality.

As to driving lower impedance, they are rated into 2 ohms NCx500 700W versus 510W 1ET6525SA. Or 28A versus ~25A peak current.


For high frequency distortion Bruno P recommends this test which Amir did below.

ah I see, do you recommend that I cancel my order and get the NCx500?

thanks

 

[Matias]

I am just arguing that technically the distortion is similar, power is higher on the NCx500, and idle consumption a little lower on the 1ET6525SA. AFAIK these are the only differences.

Personally I value +200W power a lot more than +7.4W loss on idle power, so NCx500 wins for me. But I am genuinely curious if that is just me or if customers chose the opposite? Or something else I am not aware of?

 

[amper42]

As I can't hear a difference between the NCX500 or 1ET6525SA, I typically pick the superior energy efficiency design which is Purifi by approx. 40% at normal listening levels.

 

[Matias]

As I can't hear a difference between the NCX500 or 1ET6525SA, I typically pick the superior energy efficiency design which is Purifi by approx. 40% at normal listening levels.

AFAIK the efficiency in output power is similar between both class D designs, only the efficiency in idle losses is +7.4W for a pair of NCx500. A light bulb turned on.

I mean, if power efficiency is the priority, ok, fair enough. I just wondered if that is really it. And maybe @amirm could start measuring idle power consumption as apparently it is a key factor when choosing competitive amps.

 

[amper42]

AFAIK the efficiency in output power is similar between both class D designs, only the efficiency in idle losses is +7.4W for a pair of NCx500. A light bulb turned on.

I mean, if power efficiency is the priority, ok, fair enough. I just wondered if that is really it. And maybe @amirm could start measuring idle power consumption as apparently it is a key factor when choosing competitive amps.

You might think the energy efficiency advantage of Purifi is only while idle? But, testing shows that's not the case. Mount a Kill-a-watt on the Purifi amp while playing your favorite tunes at normal listening levels. My Boxem Purifi shows 16W in use with 75dB sound levels. It never gets hot. It's one cool operator.

The NCx500 measures about 23W at the same listening levels. It's not a big difference but it shows up in not only wasted energy but also a much warmer running amp. My guess is the Purifi design may actually offer an overall product longevity not matched by NCx500 simply because of the added heat it generates.

If the NCx500 actually sounds better to you then buy it. But, if you can't tell the difference in a blind test why buy the unit with reduced energy efficiency and higher heat generation?

The one way I can always tell the difference between NCx500 and Purifi is run them both for an hour. Even turned on but idle will work too. Now put your hand on each case after an hour. You will immediately know which is the NCx500 by the heat on your hand.

 

[Matias]

I mean, you are right, when music is playing the idle losses are still happening, the same +7W are wasted with music playing or not. And the chassis gets warmer because of it.

But I guess then it really comes down to only extra max power versus less heat, as I suspected.

 

[amper42]

I mean, you are right, when music is playing the idle losses are still happening, the same +7W are wasted with music playing or not. And the chassis gets warmer because of it.

But I guess then it really comes down to only extra max power versus less heat, as I suspected.

If your amp is setup in a closed cabinet or tight spaces my vote would be for a Purifi - every time.
There are lots of reasons why someone might pick one of these amps over the other. However, I have not found audible dynamic range was one of them. By the time the Purifi is reaching even 30W on the Kill-a-watt it's too loud to be comfortable for my ears.

 

[Jukka]

But then you are comparing 2 modules + 1 PS against 2 modules + 2 PS, it is not the same.

The modules themselves have idle power rated Purifi 2 x 1.6W versus Hypex 2 x 5.3W, so the difference is 7.4W between similar amps. A light bulb. Is this the main difference to choose one over the other? I am curious.

That is correct. The module and PSU have a base draw and PSU has an efficiency factor for things it powers. Aux electronics within have very little draw in a plain power amp. But still it's two channels of somewhat similar power.

I've had the NC400 monos for close to 9 years now. They are still in weekly use, but I needed more channels.

My primary reasons to get this amp were, compared to competition: 1) I wanted something from Purifi and 2) utility: form factor, selectable gain, XLR.

Price difference of 100-150 € is negligible for a 10+ year investment. Both Purifi and Hypex products are fantastic to drive virtually any speakers and I got Purifis to drive subwoofers. These subs are summed to mono and are stacked, so a stereo amp is fitting. I put the monos to drive Left and Right bass woofers, so mono fits better there. Hypex plates on mains. All DIY. I turn them power amps off with power strip switch when not using them, so their consumption is also not a meaningful factor (a few hours in a week). Apollon Audio has very smart selectable RCA/XLR, selectable gain and 12 V trigger functions that makes this very versatile product. My set has digital signal paths and analog interconnects are 100% balanced.

 

[Sokel]

From what I can see in pictures, both the NCx500 and 1ET6525SA use Wima and Rubycon caps, so similar build quality.

As to driving lower impedance, they are rated into 2 ohms NCx500 700W versus 510W 1ET6525SA. Or 28A versus ~25A peak current.

I'm all for more power, just not from Hypex.
As soon as you hold the modules in your hands, Purifi screams quality and premium feel.

Hypex is nice as well but feels average, it's not only the components (which at Purifi are top-tier and at Hypex good enough, at least the ones starting with 500)
Thermally, Purifi is always the king, translated to MORE continuous power for similar thermal design.

Splitting hairs here of course.

The dream is always a crazy tech Purifi PSU to a complete Purifi built.

 

[Jukka]

Leaving your 16.5 W amplifier on 24/7 in Finland costs approximately
€1.05 to €1.40 less per month than leaving the two
28.6 W NC400 mono blocks
on.
The calculation is based on the following breakdown:

1. Energy Consumption Comparison (Monthly)

• Your Amplifier (16.5 W):
  • Daily:
    View attachment 515589
    16.5W×24hours=396Wh (0.396 kWh)
  • Monthly (30 days):
    View attachment 515588
    0.396kWh×30=11.88kWh
• NC400 Mono Blocks
  (28.6 W):
  • Daily:
    View attachment 515590
    28.6W×24hours=686.4Wh (0.686 kWh)
  • Monthly (30 days):
    View attachment 515592
    0.686kWh×30=20.58kWh
• Difference:
  View attachment 515593
  8.7kWh
  per month.

2. Estimated Cost in Finland
Electricity prices in Finland fluctuate, but for 2025–2026, a typical total price for household consumers (including energy, transmission, and taxes) is roughly 12 to 16 euro cents per kWh.
View attachment 515595Statista +1

• At 12 c/kWh:
  View attachment 515591
  8.7kWh×0.12=€1.04
  saved per month.
• At 16 c/kWh:
  View attachment 515594
  8.7kWh×0.16=€1.39
  saved per month.

3. Yearly Impact
If left on continuously, switching to the 16.5 W idle unit saves you roughly €12.50 to €16.70 per year.

Nord Pool Spot that I'm currently tired to can cost anything between EUR -60 cents to 2500 cents per kWh. On a windy summer day it's usually between 0 and 1 cents and in the winter more something like 15 to 30. Nights are cheaper than business hours. The price changes every 15 minutes. On average my energy cost is about half of the transmission cost and my family's yearly consumption is about 3700 kWh in this home. That's quite small consumption.

 

[Jukka]

I'm actively cooling my hotspots. I have total three PWM controlled coolers set like this:

The PWM controller allows the cooler run silently and consume only about 0.5 W each (PSU+controller+fan) when running steady. The case is cold to touch on each 6 sides after couple of hours. I expect long life from them This is not a pretty arrangement thou, I'll think of something later.