Short List of Amps I prefer over the Pass Labs XA25 or INT 25

Eric, i thought feedback was something to create the gain. I am too far from this field, but will try to have a look on some books (e.g. why the feedback is unavoidable).

Could something similar to switching waveform be used to create a correct and accurate digital signal from the source analog signal and "amply it digitally" without any distortion? Is there no way to amplify a digital signal directly from the digital sources (e.g., CD player), what this would really mean? Then you will again need a DAC just to output the amplified digital signal to the speakers (but i understand that "amplified digital signal" cannot exist, a binary number cannot be amplified and that that the conventional amplification is analog). 

You can have gain without feedback. There are class A, AB and D amplifiers that use no feedback.


The problem with what you propose in the 2nd paragraph above is that digital audio switches at speeds far too low to be practical to amplify directly, and at some point you do have to create an analog signal to drive your loudspeakers. So what some products do is they accept the digital input and then convert the switching of the digital to a much higher frequency that is practical for a switching power amp.  Some amount of DSP is required for this approach. But a switching amplifier itself is an analog process plain and simple.

Thanks for these notes.
Then you need a good DSP unit I guess. Perhaps in future a miracle can happen and digital speakers without any amplification will reproduce the sound. 

Meanwhile, another related practical question. Conrad Johnson preamplifiers have notably high thd I saw in specs of all the recent models et6 et7 and gat it is 0.15 (I was surprised to see this). I didn't have a chance to audition them but I assume they sound good.
Do they (do the higher order harmonics help)? I ask this question also because am considering to try one of these preamplifiers. Thanks

Then you need a good DSP unit I guess.

The DSP is built-in to such amps that have a direct digital input.

Conrad Johnson preamplifiers have notably high thd I saw in specs of all the recent models et6 et7 and gat it is 0.15 (I was surprised to see this). I didn't have a chance to audition them but I assume they sound good.
Do they (do the higher order harmonics help)?

There is a huge difference  between high THD and higher ordered harmonics! Higher ordered harmonics as distortion is bad and highly audible, but high THD might not be so bad, if the harmonic content is mostly lower orders (2nd, 3rd and 4th) as the ear is far less sensitive to them.

but high THD might not be so bad, if the harmonic content is mostly lower orders (2nd, 3rd and 4th) as the ear is far less sensitive to them.

Can we know, based on specs, whether THD referes to a lower or higher order harmonics? Is there another common parameter that refers to the higher order harmonics? I.e., is then a way to know about the "real" distortion (one we do not like) based on the specs? 

Actually no. I've been advocating for that for years, but the industry doesn't like the idea of a spec sheet that would actually tell you how the amp or preamp **sounds**.