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Switch from AHB2 to Purifi for KEF Reference 5?

t5r

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Hi everyone,
first post after long-time lurking :) Hoping that you can help me explain what I heard in an A/B demo, and how that might inform a future purchase decision.

My setup:
  • KEF Reference 5
  • 2x Rythmik F12 subs
  • Benchmark AHB 2
  • Anthem STR Preamp
  • Wiim Pro, streaming mostly Qobuz and Tidal
  • Dedicated, but suboptimal room (bay windows, glass door covered by a blackout curtain) with initial treatment (still being optimized within renters' constraints)
A friend recently brought his Apollon Purifi 1ET7040SA (3-channel version but we only used 2) to compare to the Benchmark. We went back and forth between both amps, with ARC on and off and different sub crossover settings. We roughly gain-matched most of the time.

The Apollon won me over strongly enough to make me consider switching. In our main test song, "Hotel California (Live on MTV, 1994)" on Tidal, bass appeared faster / more controlled, resulting in a much punchier kick. Guitars appeared more three-dimensional and less harsh. Overall things were a bit less "mushed together". These observations carried over to other test songs. Things sounded best when we let the speakers run full range or with a low 50-Hz crossover, it felt like the speakers were faster and more precise at handling bass than my subs were.

I'd love to tap into your collective expertise to learn from this experience:
  1. Are there technical / spec-based explanations for the difference I was hearing between the Benchmark and Apollon? For example, a difference in damping factor?
  2. The AHB2 is so well regarded in this forum. Do you consider a switch to a Purifi 7040 amp a potential upgrade or at least crossgrade? Are there downsides I need to consider?
  3. @Buckeye Amps 7040 mono blocks cost $900, while @Apollon Audio equivalent costs ~$2.7k. Outside of case build quality / design, should I expect any difference in sound?
  4. Would 9040s deliver an audible improvement over the 7040, especially with regard to the attributes observed in my comparison to the Benchmark?
Thankful for your thoughts!
 

VintageFlanker

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We went back and forth between both amps, with ARC on and off and different sub crossover settings. We roughly gain-matched most of the time
But this still is sighted listening anyway. As such, level match is worthless. ;)
should I expect any difference in sound?
Apart from max raw power... No you can't expect any.
Would 9040s deliver an audible improvement over the 7040
Absolutely not. Again, apart from raw power needed for x situation.
 
Last edited:

MaxwellsEq

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Hi everyone,
first post after long-time lurking :) Hoping that you can help me explain what I heard in an A/B demo, and how that might inform a future purchase decision.

My setup:
  • KEF Reference 5
  • 2x Rythmik F12 subs
  • Benchmark AHB 2
  • Anthem STR Preamp
  • Wiim Pro, streaming mostly Qobuz and Tidal
  • Dedicated, but suboptimal room (bay windows, glass door covered by a blackout curtain) with initial treatment (still being optimized within renters' constraints)
A friend recently brought his Apollon Purifi 1ET7040SA (3-channel version but we only used 2) to compare to the Benchmark. We went back and forth between both amps, with ARC on and off and different sub crossover settings. We roughly gain-matched most of the time.

The Apollon won me over strongly enough to make me consider switching. In our main test song, "Hotel California (Live on MTV, 1994)" on Tidal, bass appeared faster / more controlled, resulting in a much punchier kick. Guitars appeared more three-dimensional and less harsh. Overall things were a bit less "mushed together". These observations carried over to other test songs. Things sounded best when we let the speakers run full range or with a low 50-Hz crossover, it felt like the speakers were faster and more precise at handling bass than my subs were.

I'd love to tap into your collective expertise to learn from this experience:
  1. Are there technical / spec-based explanations for the difference I was hearing between the Benchmark and Apollon? For example, a difference in damping factor?
  2. The AHB2 is so well regarded in this forum. Do you consider a switch to a Purifi 7040 amp a potential upgrade or at least crossgrade? Are there downsides I need to consider?
  3. @Buckeye Amps 7040 mono blocks cost $900, while @Apollon Audio equivalent costs ~$2.7k. Outside of case build quality / design, should I expect any difference in sound?
  4. Would 9040s deliver an audible improvement over the 7040, especially with regard to the attributes observed in my comparison to the Benchmark?
Thankful for your thoughts!
You should compare gain between the two power amplifiers. From memory, the AHB2 is a low gain amplifier and the Apollon will probably allow several gain settings including a low gain setting.

Also, unless levels at the speaker are matched to within 0.1V there will be a subjective difference, even if they sound identical in loudness.
 

VintageFlanker

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From memory, the AHB2 is a low gain amplifier and the Apollon will probably allow several gain settings including a low gain setting.
So does the AHB2 :
1000027329.png

1000027330.png
1000027331.png
 

DSJR

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Buy another AHB 2 and bridge them - this design can still handle low impedances set that way it appears and the power output jumps up each 'channel' when two are used that way.
 

pogo

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Are there technical / spec-based explanations for the difference I was hearing between the Benchmark and Apollon? For example, a difference in damping factor?
Yes.

 
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