Originally Posted by kyotousa
So...I don't need any feature. Which 400 dollar amp should I buy that would sound the same as 200,000 dollars one?
If what you said were true, then we don't need to audition for amp... all of them should sound the same except for different feature. correct?
It is important to audition amps because different amps may have different abilities to drive certain speakers, and it is important to make sure the features work the way you want. Most 200,000$ amplifiers I have seen are SET amps. These have the potential to sound different that solid state amps, and they probably do. I won't go into the details of why they may sound different as there are plenty of materials out there that explain the distortion characters, amongst other things, of tube vs. solid state.
Nevertheless, If you have 4ohm or 2ohm speakers, the amplifier selection process becomes much more important. You don't want an amplifier that can only drive 8 and 4 ohm loads with good current. You would want an amplifier that could deliver appropriate amounts of current down through 1 ohm. In order to do that, the amplifier would require a large amount of heat dissipation and that requires money, especially if you want the dissipation to be passive heatsinks (without fan).
But, in the context of what I was talking about in the post you quoted, when you have speakers that are not known to be difficult to drive, room acoustics (from no treatments to having appropriate bass treatments and first reflections) will have a much more dramatic effect on sound quality than a 400$ amp to a more expensive amp. Even if the more expensive one has electronics that eq the FR, these typically make the it good for one location and much worse for others. Room treatments help to balance out the FR across the room while also helping out with reverb times. Of course, as with all things, you have to treat the room in an educated manner, not just throwing treatments randomly.
At the same volume (75dB) (level matched by voltmeter at speaker terminals to 0.1mV) in a small-medium sealed room (16x11x9), the RB-1050 amplifier by rotel sounded the same as a RB-1090 amplifier for 90db sensitive speakers with nominal 8ohm impedence with dips into the 4ohm range. Thats roughly $500 compared to $2000. Now, if I were auditioning 4ohm speakers that dip to 2ohm for a large portion of its FR, and had a larger room (open living arrangement 26x18x11), then I would get the RB-1090 or more depending on what I felt was required in that room (necessitating an in-room audition). This "upgrade" is due to needs as dictated by the room and speakers, not because of sound quality adjustments.
An extension of that session: That test was done with all the ASC treatments removed from the room. We took FR measurements with swept sine waves and the response was a terrible +/-26dB across the 100hz-20khz range that was tested. We did not do decay time testing. When the ASC treatments were replaced, the difference was astounding. In addition, objectively, the room measured +/-11dB across the 100hz-20khz range. Changing the amplifiers resulted in no difference to the FR, for example. For sound quality, I will take the room treatments over the electronics (considering my 90db 8ohm nominal speakers, small-medium room) any day. You really just need to experiment like this to find out how much you have been missing due to terrible room FR. It is an astounding result. It makes any other upgrade seem so minuscule - only change of speakers has a reasonable amount of change in sound quality.
I hope I have made myself more clear. You cannot buy an amplifier without thinking about the needs as dictated by your speaker choice and room situation. Additionally, if you want a good sounding SYSTEM, make sure your room acoustics are professionally fixed. Select speakers that you like, then select electronics that fit the needs of the speakers, the room, and your desired features.
Frenchmon, if your A/B was done sighted and not level-matched, you cannot say you heard a clear advantage from one electronics to another specifically due to listening (since your sight, and the experiment were not controlled). In order to make a scientific conclusion, you need 1 experimental (ears) with the rest controls. People's brains take visual cues immediately and unconsciously. If you know which electronics is playing, you immediately are biased unconsciously. Also, even a small disparity in levels will cause the test to be broken. A level as small as 0.1dB difference can lead to bias rather than true controlled experimentation. Just food for thought.
Furthermore, why spend 2k$ (for example) on small differences that you might get from electronics when you still have a +/- 20dB FR in your room at your listening position with uneven decay times when the same amount of money could go into carefully planed out room treatments that would improve your sound quality with definitive results? Yes, it is important to match your gear to the room requirements and speaker requirements, but going more than that represents a worse "return on investment" if you will. Unless you have very demanding speakers with a huge room, you do not need to spend large amounts of money on the amplification.