Different Amplifiers Changing the Width of Soundstage

Do amp designers voice the phase shift? 

Regarding distortion:

The low feedback amp has the wider (I can hear the other speaker) and more micro-detailed sound when standing in front on one speaker. 

The Class D amp (very low distortion but less micro-detail with smoothing effect) is the one where I can stand in front of one speaker and not hear the other one.  

Do amp designers voice the phase shift? 

You avoid phase shift either by having very wide bandwidth (in excess of 100KHz) or by having at least 35dB of feedback at 20KHz. The latter is very difficult to do BTW.

Mr. Atmasphere,

I want to thank you for your easy to understand but complete and thoughtful contributions. I understand what you say.. I'm a common man. The techno jarga goes right over my head.. If I can see it in MY head it works for me..

I honestly think it's a left handed thing for me. :-)

Regards

With one amp, I can stand directly in front of the left speaker and still hear the right speaker. 

With another amp I have, I can stand directly in front of the left speaker and it's like I can't hear the right speaker. 

Does anyone know why the different amps are behaving so differently to the same speakers?

If you have a mono recording, or used a splitter to put the same preamp channel into both amp channels, then one could measure whether the amplifier is outputting a different signal on one channel or the other.

 

Subtle changes in the distortion and the slewing of the transients and micro transients. Additionally, with one channel vs the other (as an extra potential aspect). 

I am not even sure I know what ^this^ Is supposed to mean. What are micro transients and and what is being slewed? Voltage, phase, or what?