Apollon 1ET6525SA ST Amplifier Review

[amper42]

Well, I’d like to replace the Sonic Imagery 994 op-amps with the OPA 1656.
I just don’t know the correct procedure.
I don’t wanna break anything in the amplifier.

Why not ask Apollon for help?
A simple search offers the following:

Step-by-Step Installation:

1. Prepare the Unit: Turn off the audio device and unplug it from the power source. Let it sit for several minutes to allow capacitors to discharge.
2. Access the Board: Remove the chassis cover to expose the circuitry, as detailed in this Apollon Audio guide.
3. Remove the Sonic Imagery 994: Using gentle, even pressure, pull the 994 modules straight up and out of their sockets to avoid damaging the pins.
4. Prepare the OPA1656: Ensure your OPA1656 is mounted on a DIP-8 dual op-amp adapter.
5. Identify Pin 1 Orientation: Identify Pin 1 on the OPA1656 adapter (usually marked with a dot or a small indentation) and align it with the half-moon cutout or notch on the PCB DIP-8 socket.
6. Insert the Op-Amp: Carefully align all 8 pins of the OPA1656 adapter with the socket holes, ensuring no pins are bent, and push down gently until secure.
7. Final Checks & Power On: Double-check that the orientation is correct to avoid damaging the chip. Reinstall the cover and power on, testing for sound.

If this still feels uncomfortable ask Apollon for help or a local tech.
It's possible you may not hear much difference, so I would not be too focused on making this change if you're already happy with the amp's current operation.

 

[amper42]

Can anyone tell pls tell me which gain sttings would be best for balanced connection to an AV30 vs unbalanced RCA to a Cinema 30 pls
Thanks Al

I would suggest using 20.5 dB gain setting with AV30 and 29 dB gain with Cinema 30.

 

[Apollon Audio]

OPA1656 offers better measurements. It's funny though some people actually prefer the increased harmonic distortion of the Sonic Imagery 994 op-amps.

Purifi Eigentakt 1ET6525SA ST Stereo Amplifier

The Apollon Audio Purifi 1ET6525SA Stereo Amplifier is built around the amazing Purifi 1ET6525SA amplifier module in a very compact and light weight design with amazing clarity and brutally linear sound.

apollonaudio.com

"Our custom input buffer board by default comes with the very advanced OPA 1656 operational amplifiers. But if you would at any time wish to change the sound characteristics of the Apollon 1ET6525SA ST amplifier you can do so with simply exchanging the op amp (so called Op amp rolling). Our custom input buffer board comes with a DIP8 socket that enables you to attach a wide range of DIP8 compatible operational amplifiers on the market."

Actually Sonic Imagery measures slightly better.

 

[amper42]

Actually Sonic Imagery measures slightly better.

THD+N vs. Frequency: Graphs often show at high frequencies (above 15 kHz) and low frequencies (below 500 Hz), the discrete SI 994 measures slightly worse with higher distortion than the OPA1656.

Do you have internal measurement graphs at Apollon that you could share? Thank you!

 

[Ruediger]

Prices on www.apollonaudio.com are excluding VAT and shipping.

And paypal fee, if that is used.

 

[JensA]

Attached photos of my Purifi 1ET9040BA Eigentakt Home Cinema LCR Premium Amplifier Apollon PET1203 which I received last month.

Superb built quality and more than sufficient power than I will probably ever need

The two amps belong to Apollon's "Premium" line, so I could have saved $$$ by chosing one of Apollon's (or any other reliable maker's) cheaper ET9040 amps without compromising on "sound quality", but I simply like the look and feel. Besides even these premium level amps are much cheaper than the amps they have replaced...

 

[haris525]

Attached photos of my Purifi 1ET9040BA Eigentakt Home Cinema LCR Premium Amplifier Apollon PET1203 which I received last month.

Superb built quality and more than sufficient power than I will probably ever need

The two amps belong to Apollon's "Premium" line, so I could have saved $$$ by chosing one of Apollon's (or any other reliable maker's) cheaper ET9040 amps without compromising on "sound quality", but I simply like the look and feel. Besides even these premium level amps are much cheaper than the amps they have replaced...


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looks fantastic man! waiting for Mine - it seems the US deliveries can take much longer vs EU deliveries. Hopefully soon!

 

[LucreciaBorgia]

I pulled the trigger and ordered the big brother 1ET9040 in the Lux version, pearl white....The casing made the difference for me, I find the design very "stylish" and in this pearl white version, looks really good (in my opinion, of course...). Let's see how it sounds, and I hope it will not have the same issues I have had with the BoXem monoblocks !

 

[JensA]

looks fantastic man! waiting for Mine - it seems the US deliveries can take much longer vs EU deliveries. Hopefully soon!

Not really:
I’m absolutely delighted with the two amplifiers, but there’s still plenty of room for improvement when it comes to Apollon’s communication regarding delivery dates.
In the end, it took nearly three months for the amps to be delivered. It’s not a problem at all; you just need to communicate clearly.
I also wrote this in my review on the Apollon website.

 

[Ruediger]

I pulled the trigger and ordered the big brother 1ET9040 in the Lux version, pearl white....The casing made the difference for me, I find the design very "stylish" and in this pearl white version, looks really good (in my opinion, of course...). Let's see how it sounds, and I hope it will not have the same issues I have had with the BoXem monoblocks !

Stunning box! Not only the looks but also the specs of course. Hope it will last for decades.

Personally I went with the reviewed model here in the more basic case.

 

[amper42]

Attached photos of my Purifi 1ET9040BA Eigentakt Home Cinema LCR Premium Amplifier Apollon PET1203 which I received last month.

Superb built quality and more than sufficient power than I will probably ever need

The two amps belong to Apollon's "Premium" line, so I could have saved $$$ by chosing one of Apollon's (or any other reliable maker's) cheaper ET9040 amps without compromising on "sound quality", but I simply like the look and feel. Besides even these premium level amps are much cheaper than the amps they have replaced...


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The RCA Jacks look too close to speaker terminals?
Not the layout I would want.

 

[Descartes]

I would choose the Apollon 1ET6525SA. With limited ventilation, keeping thermal stress in check is important—heat has always been the silent killer of gear. My speakers don’t demand more than 250 watts, and I have no intention of pushing them anywhere near that. These days, I prefer refinement and longevity over sheer output. Finally, as a physician, I’m mindful of preserving my hearing and avoiding tinnitus over the long term.

Wishing that I had been more knowledgeable in my youth and protected my hearing. Loved to go to clubs and the music was always so loud that my ears would be ringing for hours afterwards.

 

[Descartes]

Stunning box! Not only the looks but also the specs of course. Hope it will last for decades.

Personally I went with the reviewed model here in the more basic case.

Now if Buckeye was willing to trade the utilitarian boxes for these and charge a couple hundred dollars more I would be all over it!
What concerns me with stuff coming from an unknown company in China is customer service & longevity

 

[GS430man]

Apollon has good products. Buckeye has good products.

The market has room for both. More consumer choices = good!

 

[LucreciaBorgia]

Now if Buckeye was willing to trade the utilitarian boxes for these and charge a couple hundred dollars more I would be all over it!
What concerns me with stuff coming from an unknown company in China is customer service & longevity

???
Apollon is not unknown, and is not chinese...

 

[Mike_Trueman]

Yeah for me Apollon and NAD make the nicest enclosures and cases for Eigentakt/Hypex power amps.

 

[Descartes]

Yeah for me Apollon and NAD make the nicest enclosures and cases for Eigentakt/Hypex power amps.

Aggeed but the up charge is a bit much!

 

[Descartes]

Attached photos of my Purifi 1ET9040BA Eigentakt Home Cinema LCR Premium Amplifier Apollon PET1203 which I received last month.

Superb built quality and more than sufficient power than I will probably ever need

The two amps belong to Apollon's "Premium" line, so I could have saved $$$ by chosing one of Apollon's (or any other reliable maker's) cheaper ET9040 amps without compromising on "sound quality", but I simply like the look and feel. Besides even these premium level amps are much cheaper than the amps they have replaced...


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They are beautiful how much more were they than their non luxury line

 

[harkpabst]

Aggeed but the up charge is a bit much!

As has been discussed before: No, not really, comparing apples with apples.

 

[SKNG]

The RCA Jacks look too close to speaker terminals?
Not the layout I would want.

Unless the layout is different between premium version monoblocks, stereo or multi channels amp, taking my monoblocks as example there's enough clearance for the RCA jack even using thicker spk cable with large spades.