Is the color in the amp , the preamp, the souce?

Baxter178 - Lots and lots of issues are raised by your post. It's obvious you have asked these questions in earnest, so I hope fellow A'goners will keep that in mind when responding (I've noticed things have been a bit volatile around here lately).

By way of response, I can recommend that you take a look at this thread. It has a long and detailed discussion of coloration, neutrality, accuracy, and other concepts relevant to your questions. As you will see from even a brief perusal, this is a complicated subject with widely diverging points of view.

1)There's no such thing as neutrality - all components render a sonic signature of some sort, and every one is different. The only thing that sounds the same is all of those doubting Thomas's who say that "all __x__ sound the same". Many devices may sound the same to the untrained ear, and not all listeners are as sensitive to these sonic differences. This is where the argument can certainly become ugly.

2)The trick to this is to find a desirable synergy between all of your componentry, that which matches up with your sonic preferences. So that signature which you prefer doesn't necessarily match up with one that I, or anyone else, would prefer. You have to please yourself, and nothing else really matters. The colorations of componentry, cabling, and speakers all combine into the overall sonic signature which you hear. Your goal is to find the characteristics that you like, then combine (synergize) them into your overall perferred sound. This is not easy.

3)"Better" is what sounds better to YOU alone. So even if the front end is all the same, speakers are the same, cabling is the same, and the listening room is the same, then simply changing the amp alone will indeed result in a different overall signature. Why? Many contributing factors go into these variables such as design, component variations, and the interaction between the reactive characteristics of upline cabling, the component in question, and the downline cabling.

4)Ignore the specifications; that has little to do with it. Much componentry, cabling, and speakers are all well designed & built in the present state of the art. Power output levels are not so much of a contributing factor either, except at the extremes where headroom and clipping come into play.

5)It will take you years to understand all of this, and even then you'll only have a clue. No one knows all the answers, and the more you know the more questions you'll have. Read these forums often, and do avail yourself of the multitude of knowledge found in the forum archives. That is what they are there for and you will learn a lot therein. Enjoy it: it is a lot of fun, it is at times confusing, and everyone has differeing views so keep that in mind. It's all about opinions, and everybody's got one.

I have a hard time understanding (all specifications being equal) how an amplifier can sound different.

First let me say that I second and applaud Bryon’s admonition to others who may respond.

Here are some reasons that come to mind as to why similarly spec’d amplifiers may sound different. There are undoubtedly a great many others, both known and generally understood, and unknown/unexplainable:

1)Amplifier specs are generally based on the assumption that the speaker has a resistive 8 ohm or 4 ohm impedance. Real-world speakers have significant reactive (inductive and capacitive) impedance components, which vary widely among different speakers, and, for a given speaker, vary widely with frequency. Loads having significant reactive impedance components are more difficult to drive than purely resistive loads, and different amplifiers will have differing degrees of success doing so.

2)Harmonic distortion created by an amplifier is commonly spec’d in the form of TOTAL harmonic distortion (THD). However, the audible significance of THD is highly dependent on WHICH harmonics are present in the distortion spectrum, and to what degree.

3)Different amplifier designs use differing amounts of feedback. Feedback can reduce THD, improve linearity, and lower output impedance. However, it can introduce or worsen Transient Intermodulation Distortion (TIM), which is not generally specified and which subjectively can be more objectionable than the effects that are helped by feedback. A high quality design will need little or no feedback to minimize those effects, and will therefore have minimal TIM, but will tend to be more expensive.

4)Amplifier output impedance (equal to “damping factor” divided into 8 ohms) is a parameter that is fundamental to the interaction of amplifier and speaker. Although damping factor is usually specified, the specs for different amplifiers vary widely, and precise prediction of what combination of output impedance and speaker will be most synergistic is generally not possible.

5)Different amplifier classes are subject to differing kinds of distortion.

6)Amplifier power supplies generate high frequency noise, due to an effect known as “rectifier commutation,” which, depending on its frequency components and amplitude, can radiate or couple into circuit points in other parts of the system, with unpredictable results.

7)Ultrasonic or rf spurii that may be fed into or picked up by the amplifier can intermodulate with the audio signal, resulting in effects within the audible spectrum. The degree to which that happens will be dependent on the bandwidth, the circuit topology, the physical layout, and other characteristics of the amplifier.

8)Unspecified stray capacitances in the amplifier’s power transformer will affect sensitivity of the system to ground loop-related hum and buzz (subjectively affecting background “blackness”).

9)The behavior of different amplifiers when over-driven or clipped will vary significantly, particularly when comparing tube and solid state designs.

10)Amplifiers have differing amounts of “dynamic headroom,” meaning the ability to deliver greater amounts of power than their continuous power rating, for limited amounts of time. Dynamic headroom may or may not be specified, but even if it is, amplifiers with similar amounts of specified headroom will vary widely in terms of how long that increased power level can be supplied for.

11)Parts quality will affect sonics in ways that are not readily specifiable or predictable.

As I said, there are many more known and unknown reasons for sonic differences between similarly specified amplifiers, but hopefully these will give you a general flavor.

Regards,
-- Al