Apollon 1ET6525SA ST Amplifier Review

[Descartes]

When selling across the EU, VAT is not a single fixed rate. It varies depending on the customer’s country (19%, 20%, 22%, 25%, etc.).

Under the EU OSS system, VAT must be applied according to the buyer’s location, which means the correct VAT rate can only be determined at checkout once the country is known.

For customers outside the EU, VAT is not applied at all. Because of this, displaying a single VAT-included price would actually be inaccurate for a large portion of customers.

This is why many international webshops calculate VAT during checkout rather than showing one fixed VAT-included price.

Love the look of your amplifiers but they are too expensive compared to Buckeye

 

[Apollon Audio]

Love the look of your amplifiers but they are too expensive compared to Buckeye

Thank you, I appreciate the kind words about the design.

Regarding pricing, the difference between our Purifi 1ET6525 amplifier and the Buckeye version is actually quite small. Our unit is currently €1090, while Buckeye’s comparable model is about €1042, so we are talking about roughly a €48 difference.

At the same time, we use significantly more expensive components in several areas:

• Higher-grade connectors and terminals
• A more complex and better enclosure
• Higher machining and finishing quality
• More expensive internal wiring and hardware

These choices increase manufacturing cost, but they also improve durability, usability, and overall build quality.

Different manufacturers simply prioritize different things. Our goal has always been to combine top tier Purifi performance with premium build quality, while still keeping the price very competitive.

 

[antcollinet]

Hi do the tweak really introduce "tubelike smoothness*?

No. There is essentially no such thing - unless you mean a slight roll off in the highs - which if you want that is better done via eq or tone control.

 

[WillBrink]

Love the look of your amplifiers but they are too expensive compared to Buckeye

I'd pay the extra $ for the much improved case and looks if I were in the market for a new amp. I do wish Buckeye offered an up market case.

 

[J84]

No. There is essentially no such thing - unless you mean a slight roll off in the highs - which if you want that is better done via eq or tone control.

Thanks

 

[AcousticTheory]

Love the look of your amplifiers but they are too expensive compared to Buckeye

I think you've hit upon something; a nicer package is going to cost more money. But consider that the enclosure is the part of the amplifier you'll interact with the most, and a functional enclosure with good cooling and a nice finish to look at starts to seem like a worthy expenditure. By comparison, Buckeye's zero-splurge enclosure is mainly to keep your fingers away from the components.

If you just need the cheapest possible amp, then in theory you could buy modules off the secondary market and splice your own power plug into the connectors and spark them up using the switch on a power strip; the cheapest enclosure would be no enclosure at all. Not that it's safe or advisable or anything.

 

[huw]

f you just need the cheapest possible amp, then in theory you could buy modules off the secondary market and splice your own power plug into the connectors and spark them up using the switch on a power strip; the cheapest enclosure would be no enclosure at all. Not that it's safe or advisable or anything.

I think this sort of comment illustrates how slim the margins are on these amplifiers. Anyone can buy the following direct from the manufacturer:

Hypex SMPS1200A400 €199
2x Purifi 1ET6525SA 2 x €292
Total = €783

So yes if you can source the input buffer and input and output connectors for ~ €85 which is the difference between a Purifi EVAL6 Stereo 1ET6525SA evaluation kit and the cost of the amplifier modules you could save maybe €200 without buying an enclosure and get a functional (for as long as you managed the heat dissipation) amplifier. The case and assembly time is a substantial part of the final cost of the amplifier before even considering the cost of sales/aftersales support etc.

Given that, I don't think the @Buckeye Amps/@boXem A-series/ @Apollon Audio non-Lux (sorry I didn't know what else to call this!) Purifi 1ET6525SA stereo amps are really that different in price? They all use their own input boards so the cost of development and manufacturing of these has to be distributed over the sales of the completed amplifiers. I imagine all these companies aim is to offer a stereo Purifi 1ET6525SA amp for as competitive a price as they can.

 

[Jukka]

I think this sort of comment illustrates how slim the margins are on these amplifiers. Anyone can buy the following direct from the manufacturer:

Hypex SMPS1200A400 €199
2x Purifi 1ET6525SA 2 x €292
Total = €783

So yes if you can source the input buffer and input and output connectors for ~ €85 which is the difference between a Purifi EVAL6 Stereo 1ET6525SA evaluation kit and the cost of the amplifier modules you could save maybe €200 without buying an enclosure and get a functional (for as long as you managed the heat dissipation) amplifier. The case and assembly time is a substantial part of the final cost of the amplifier before even considering the cost of sales/aftersales support etc.

Given that, I don't think the @Buckeye Amps/@boXem A-series/ @Apollon Audio non-Lux (sorry I didn't know what else to call this!) Purifi 1ET6525SA stereo amps are really that different in price? They all use their own input boards so the cost of development and manufacturing of these has to be distributed over the sales of the completed amplifiers. I imagine all these companies aim is to offer a stereo Purifi 1ET6525SA amp for as competitive a price as they can.

Yes and also everyone should remember that if you buy an amplifier that you're going to be looking at the next 10 years, what is 150 € if it's that much to make it pleasing to the eye?

 

[Descartes]

Yes and also everyone should remember that if you buy an amplifier that you're going to be looking at the next 10 years, what is 150 € if it's that much to make it pleasing to the eye?

Yep my amplifiers are going on 15 years

 

[DavidEdwinAston]

 

[DavidEdwinAston]

Pure beauty.

 

[harkpabst]

And purely off-topic?

 

[DavidEdwinAston]

And purely off-topic?

Forgive me. I have sinned!

 

[harkpabst]

Forgive me. I have sinned!

Troll.

 

[DavidEdwinAston]

Troll.

Probably takes one to know one.

 

[AkodoGilador]

I think you've hit upon something; a nicer package is going to cost more money. But consider that the enclosure is the part of the amplifier you'll interact with the most, and a functional enclosure with good cooling and a nice finish to look at starts to seem like a worthy expenditure. By comparison, Buckeye's zero-splurge enclosure is mainly to keep your fingers away from the components.

If you just need the cheapest possible amp, then in theory you could buy modules off the secondary market and splice your own power plug into the connectors and spark them up using the switch on a power strip; the cheapest enclosure would be no enclosure at all. Not that it's safe or advisable or anything.

The main purpose of the enclosure is to keep RFI away from the components. See, eg https://www.audiosciencereview.com/...ai500diy-amplifier-review.41669/#post-1473510:

Alex

 

[Apollon Audio]

The enclosure in a Class D amplifier serves multiple critical functions beyond simple mechanical housing.

First, it acts as an effective electromagnetic shield, preventing both the emission and ingress of radio-frequency interference (RFI/EMI). Class D amplifiers operate with high-frequency switching, which inherently generates electromagnetic noise. A properly designed conductive enclosure (typically aluminum or steel) functions as a Faraday cage, significantly reducing interference with both the amplifier’s own sensitive input stages and nearby audio equipment. This is particularly important for maintaining low noise floor and preserving measured performance.

Second, the enclosure plays an important role in thermal management. While Class D amplifiers are highly efficient, the output stage and associated components (such as MOSFETs and inductors) still dissipate heat under load. The enclosure, often coupled thermally to the module via mounting points or thermal pads, acts as a passive heatsink. Without adequate thermal coupling to the enclosure, heat buildup can occur more rapidly, leading to thermal limiting or reduced continuous output power capability.

In fact, operating the module outside of an enclosure, or in an enclosure with insufficient thermal mass or airflow, can significantly reduce sustained power performance, as thermal protection mechanisms will engage earlier.

Lastly, the enclosure contributes to mechanical stability and durability, as well as protection against electrostatic discharge (ESD) and environmental factors such as dust and accidental contact.

In summary, the enclosure is an integral part of the amplifier’s electrical, thermal, and mechanical design, not merely an aesthetic or structural element.

 

[antcollinet]

The enclosure in a Class D amplifier serves multiple critical functions beyond simple mechanical housing.

First, it acts as an effective electromagnetic shield, preventing both the emission and ingress of radio-frequency interference (RFI/EMI). Class D amplifiers operate with high-frequency switching, which inherently generates electromagnetic noise. A properly designed conductive enclosure (typically aluminum or steel) functions as a Faraday cage, significantly reducing interference with both the amplifier’s own sensitive input stages and nearby audio equipment. This is particularly important for maintaining low noise floor and preserving measured performance.

Second, the enclosure plays an important role in thermal management. While Class D amplifiers are highly efficient, the output stage and associated components (such as MOSFETs and inductors) still dissipate heat under load. The enclosure, often coupled thermally to the module via mounting points or thermal pads, acts as a passive heatsink. Without adequate thermal coupling to the enclosure, heat buildup can occur more rapidly, leading to thermal limiting or reduced continuous output power capability.

In fact, operating the module outside of an enclosure, or in an enclosure with insufficient thermal mass or airflow, can significantly reduce sustained power performance, as thermal protection mechanisms will engage earlier.

Lastly, the enclosure contributes to mechanical stability and durability, as well as protection against electrostatic discharge (ESD) and environmental factors such as dust and accidental contact.

In summary, the enclosure is an integral part of the amplifier’s electrical, thermal, and mechanical design, not merely an aesthetic or structural element.

You seem to be missing possibly the most important function - at least for any device with a built in PSU - and that is protection of the user from the internal dangerous voltages.

 

[Matias]

You seem to be missing possibly the most important function - at least for any device with a built in PSU - and that is protection of the user from the internal dangerous voltages.

"protection against ... environmental factors such as ... accidental contact."

 

[antcollinet]

"protection against ... environmental factors such as ... accidental contact."

Since that was bunched together with mechanical stability/durability, and protection from dust - I took it as meaning protection for the device from accidental contact by other stuff (coins causing shorts, hard/heavy objects causing physical damage. etc). rather than protecting the user.

but my reading of it may not have been what was intended.