@David A - I agree with you, I am quite sure that the ability to run a high rated power output at high frequencies is utterly irrelevant to sound quality. This was part of the point I was making regarding the power of the words that surround the measurements, Stereophile write "a peak level of 20W into 4 ohms (the highest level the amplifier would deliver with this signal without the power supply collapsing)" and nobody notices or cares. Posters on ASR write something like "ha ha ha - a ten-thousand-dollar amp that collapses at 6W at 20kHz - French fail!" - Then suddenly we take notice. Does it matter to sound quality? No, I cannot see that it does. Plus, we still do not know why the ASR reviewed amp failed. I think it is best to revisit this point when we have more information. In terms of what really interests me, see my comments below.
@ssfas - I agree with your subjective observation regarding transient speed. This is one of the things that appealed to me about the Devialet during my very first audition of a D240 Expert, it just sounded more exciting and alive versus some similarly priced rivals. This is more in line with the question that interests me, what is it in the measurements that reveals this aspect of amplifier performance? In a similar way, I found the Expert to be maybe a bit smoother and more relaxed than my current Pro, whereas the Pro seams more detailed and revealing. What in the many available measurements reveals the reason for this?
Furthermore, I am pretty certain that if you listened to two amplifiers, one with a signal to noise ratio of 130dB, the other 115dB but otherwise identical in performance, it would be impossible to tell them apart. Yet on paper, the first example is clearly superior. The same thing with THD figures of 0.0001 versus 0.01 and similar.
As another example, there was one time I listened to a Chord SPM1200 back to back with a Bryston 4BSST, with no other changes made to the overall system. To me the Bryston has slightly more pronounced mid bass, whereas the Chord seemed to go deeper with better bass definition. I note that the Bryston has an output impedance of 0.06 ohms, the Chord slightly better at 0.04 ohms. Is this the reason for the subjective difference? Who knows? I could also say the Devialet Expert is the best of the lot for this aspect of bass depth and accuracy (which I subjectively believe to be true), and look, it has an output impedance of 0.01 ohms. So here we have full correlation between my subjective observations and the measurements, the lower the output impedance, the better the low bass accuracy. The trouble is that this does not prove causality, it might just be coincidental, or my ears and brain tricking me. I suspect there is something in this, but as I said before, who knows?
From what I have read to date, nobody has a clear answer to the question of exactly how all aspects of sound quality relate to specific measurements. Lots of ideas, speculation and opinions, but nothing definitive. In fact, I suspect that it would take a considerable amount of very expensive research to resolve this one
This is why I think sites like ASR would be a lot more interesting if there was a greater mix of the objective with the subjective, to try to improve understanding of how they correlate. Meanwhile, just stating amp A crushes amp B because it has a better SINAD number is a little misleading. OK – ASR measure a lot more than this, and some ASR posters appear to be very knowledgeable. Unfortunately, one or two ASR posters seam to fail to realise the full complexity of the subject, or at least do not wish to debate the subtleties, and this combined with an apparent joy for arguing and trashing the reputation of anything expensive, it can get a little ugly, and this shuts down the more nuanced debate. I think with a slight change of attitude and moderation, ASR could be excellent. However, this does not look likely, so we are left with the ASR we have, it is what it is.
@ssfas - I agree with your subjective observation regarding transient speed. This is one of the things that appealed to me about the Devialet during my very first audition of a D240 Expert, it just sounded more exciting and alive versus some similarly priced rivals. This is more in line with the question that interests me, what is it in the measurements that reveals this aspect of amplifier performance? In a similar way, I found the Expert to be maybe a bit smoother and more relaxed than my current Pro, whereas the Pro seams more detailed and revealing. What in the many available measurements reveals the reason for this?
Furthermore, I am pretty certain that if you listened to two amplifiers, one with a signal to noise ratio of 130dB, the other 115dB but otherwise identical in performance, it would be impossible to tell them apart. Yet on paper, the first example is clearly superior. The same thing with THD figures of 0.0001 versus 0.01 and similar.
As another example, there was one time I listened to a Chord SPM1200 back to back with a Bryston 4BSST, with no other changes made to the overall system. To me the Bryston has slightly more pronounced mid bass, whereas the Chord seemed to go deeper with better bass definition. I note that the Bryston has an output impedance of 0.06 ohms, the Chord slightly better at 0.04 ohms. Is this the reason for the subjective difference? Who knows? I could also say the Devialet Expert is the best of the lot for this aspect of bass depth and accuracy (which I subjectively believe to be true), and look, it has an output impedance of 0.01 ohms. So here we have full correlation between my subjective observations and the measurements, the lower the output impedance, the better the low bass accuracy. The trouble is that this does not prove causality, it might just be coincidental, or my ears and brain tricking me. I suspect there is something in this, but as I said before, who knows?
From what I have read to date, nobody has a clear answer to the question of exactly how all aspects of sound quality relate to specific measurements. Lots of ideas, speculation and opinions, but nothing definitive. In fact, I suspect that it would take a considerable amount of very expensive research to resolve this one
This is why I think sites like ASR would be a lot more interesting if there was a greater mix of the objective with the subjective, to try to improve understanding of how they correlate. Meanwhile, just stating amp A crushes amp B because it has a better SINAD number is a little misleading. OK – ASR measure a lot more than this, and some ASR posters appear to be very knowledgeable. Unfortunately, one or two ASR posters seam to fail to realise the full complexity of the subject, or at least do not wish to debate the subtleties, and this combined with an apparent joy for arguing and trashing the reputation of anything expensive, it can get a little ugly, and this shuts down the more nuanced debate. I think with a slight change of attitude and moderation, ASR could be excellent. However, this does not look likely, so we are left with the ASR we have, it is what it is.
1000 Pro - KEF Blade - iFi Zen Stream - Mutec REF10 - MC3+USB - Pro-Ject Signature 12
