Looks like we're back to the age old dilemma that audio has been struggling with since the 50s.
Human perception vs scientific measurement. Everyone is familiar with the distortion measurements vs audibility arguments made for amplifiers. All amps don't sound the same to all people, even with identical distortion measurements. Probably because we still cannot measure everything the human ear can discern.
Engineers (of which I am one) are trained to focus on the "main effects" that have the highest probability of being dominant. Most EEs will not consider the impact of transient line noise at megahertz frequencies and millivolt levels on a power supply, and that even some of the best filters may not remove every trace, to the exclusion of a human listening to the amp connected to that line source. Or that the transient demand of a large power amp for current through its tranformer/power cord might create transient effects in the power system that effects the amp circuitry, and that these effects may be percieved by a listener. Or that these effects may be influenced and determined by the line cord's impedance just as it is with cables connected to the speakers.
True, the purpose of most power supply designs is to minimize the impact of these variables on the amps themselves, but that does not mean that every amp design is successful in doing it to the level that such remnants are inaudible by trained listeners.
However, as is widely known, determination of FACT based soley on human perception is fraught with false thinking as well. Just ask a police officer who has dealt with multiple witnesses who provide radically different perceptions of the same event. Add to this the complications of motive based perception, someone having spent $1000 on a power cord is not likely to freely admit it sounds no better than the $6 EIC cord than came with the amp.
This dilema continues and will not be resolved any time soon. I like to take heart in the musings of folks like Pass and Curl, who base designs on solid engineering principles and accepted sonic vs hardware relationships, but still are open minded with regards to the impact of these things on the human perception of listening. We are always discovering new relationships between the physical designs and hardware, and how these relate to human perception.
Human perception vs scientific measurement. Everyone is familiar with the distortion measurements vs audibility arguments made for amplifiers. All amps don't sound the same to all people, even with identical distortion measurements. Probably because we still cannot measure everything the human ear can discern.
Engineers (of which I am one) are trained to focus on the "main effects" that have the highest probability of being dominant. Most EEs will not consider the impact of transient line noise at megahertz frequencies and millivolt levels on a power supply, and that even some of the best filters may not remove every trace, to the exclusion of a human listening to the amp connected to that line source. Or that the transient demand of a large power amp for current through its tranformer/power cord might create transient effects in the power system that effects the amp circuitry, and that these effects may be percieved by a listener. Or that these effects may be influenced and determined by the line cord's impedance just as it is with cables connected to the speakers.
True, the purpose of most power supply designs is to minimize the impact of these variables on the amps themselves, but that does not mean that every amp design is successful in doing it to the level that such remnants are inaudible by trained listeners.
However, as is widely known, determination of FACT based soley on human perception is fraught with false thinking as well. Just ask a police officer who has dealt with multiple witnesses who provide radically different perceptions of the same event. Add to this the complications of motive based perception, someone having spent $1000 on a power cord is not likely to freely admit it sounds no better than the $6 EIC cord than came with the amp.
This dilema continues and will not be resolved any time soon. I like to take heart in the musings of folks like Pass and Curl, who base designs on solid engineering principles and accepted sonic vs hardware relationships, but still are open minded with regards to the impact of these things on the human perception of listening. We are always discovering new relationships between the physical designs and hardware, and how these relate to human perception.