Difference between amps


OK so let's talk amps.  I'm sure this has been addressed before but are there real differences between  multi-channel amps among the various brands in the mid-fi to high end markets with comparable specifications? Adcom, Anthem, Classe, Emotiva, Krell, McIntosh, Marantz, NAD, Parasound, Outlaw, Rotel, etc.  What are the differences in these brands?   I can site one difference.  In multi-channel Marantz amps, the specs never state "all channels driven".  They are notorius for misleading the consumer with their power output ratings.  But that's a marketing decision. What are the real or should I say physical or performance differences among these?  .  
pdn
The difference is sound, price, performance, layout, and aesthetics. 
If you are looking for a model by model comparison between 7 manufacturers, I can’t help you there. 
"...I can site one difference. In multi-channel Marantz amps, the specs never state "all channels driven". They are notorious for misleading the consumer with their power output ratings..."

Mass consumer products are made for the mass consumer, not top quality audio. You will find nothing on the spec sheet that will tell you anything about their sound quality or ability to drive a loudspeaker except in very general terms. 
When i was going on the look and search for a really good amplifier at low cost, my only possibility was used, but more than used, vintage and a vintage piece miraculously under evaluated...

I have chose mine after 2 years of search, reading ALL reviews about the main vintage legends and ,mythical products, from the tube Fischer amplifier to the Sansui last model....

It is near impossible to buy an amplifier today without listening to it extensively or if not, then put our faith on a few reviews because the product is new...Is this product would be sold as a mythical good one in 50 years? Or would it be forgottent with the mass of good amplifiers but only good not extraordinary good?


With all this thinking i catched a strike with the Sansui AU 7700... At 100 bucks....

It is my really first good amplifier and perhaps my last.... I bought another one 300 bucks in case so good is the first....

😊

In 1968 Sansui was in the top high end and in the mass market of top high end.... His products were sought and it is so true that the name become synonym of fiability, flexibility, organic sounding first, and refined organic sounding at his best.....It was.... It is till this day in my room....

No product at all actually in the market give so much flexibility and high quality for so little money, better than that no product at any cost give the flexibility and not ONLY good sound.....

Think about that..... I feel right with this purchase more than ever.....

Anyway to come back to the question in this thread most of us cannot afford to compare many amplifiers, and the way an amplifier will be listen to is always indirectly, trough a room, through some specific speakers, and specific analog or digital source? And least but not last,how can we assess his real S.Q. trough a not so perfectly embedded audio system ?

The best method is to buy a product very, very, high end or costly, non criticable design or a vintage legend that cannot deceive , between these two alternatives, beware.....

Actual mass market amplifiers has nothing to do with 50 years old mass market amplifiers for many reasons.... Quality is not the main flag here and now but profit except for very costly high end craftsman product but they dont hope to mass market anymore for decades now.... It is no more either the same people that bought audio.... They sought for efficiency more than elusive refinement.... Audiophile is now an insult.... It was not so 50 years ago.... Correct me if i am wrong, you are welcome....

By the way it seems there exceptions to what i speak about, i dont doubt that Schiit for example may sell quality products and develop a mass market but no way this amplifier can compare to the best of Sansui at all level....It is my opinion only i am not necessarily right like i already said....

My best to all...