Does anyone care to ask an amplifier designer a technical question? My door is open.

@mapman

I use the receivers only as a simple demonstration of the benefits of more clean power in a line that otherwise is mostly similar in design.

Just my gut feel but I suspect there are many who have underpowered systems that clip perhaps in often subtle ways and then blame the results on a bad recording and never know it. Been there, done that myself in the past for sure as well.

Whereas not taking chances with clipping even in its most subtle form is perhaps the single biggest key to getting the best possible results. That and keeping noise to a minimum which is much harder to do in any high power integrated amp or receiver with more circuit and components in closer proximity to each other compared to separate devices

Sorry but this is not consistant with my experience. 

I find from conversations with customers that they are actually using only a fraction of the power they think they are using. In otherwords they have tons of headroom they did not think they have. Once again we do have tools to measure these things and guessing is just not good. Happy to hear any numbers you care to share in your system.

I studied clipping in many classic amplifiers and in my own of course. When tube amplifiers clip they often take a long time to recover. The highly respected HK Citation tube amps are horrible clippers with very slow recovery, the ST-70 is not so good either but recovers faster. A few amps that handle clipping softly with virtually no recovery time are the Marantz and so few others I cannot even recall them. I have measured over 100  power amps in 400 pages of notes. Before I embarked on the RM-9 I had the opportunity to play with a Marantz 5 which is a mono 8. It blew me away comparet to the Dynaco and other amps I had measured. When I designed the RM-9 I was very interested in doing as well as Marantz (SId Smith) and I feel I did. Sid Smith set a standard that might just be unbeatable for clipping and recovery. I would say if you amp never never clips you have too much amp.

So to sum it up. Good amps can clip a bit, Most people don't here clipping if it is gentle and recovers fast. Extreme headroom means nothing and may acually be a detriment due to making an amplifier far larger than it need be. I have never found a good argument for excess in anything. Thats just philosophical. I like to live lightly on this Earth. Over powered systems impress me not.

@btp24

Roger, why is damping such an outdated term? ;-) I have heard you speak of how even a low output impedance amp doesn't, contrary to common believe, "damp" a woofer. You have quoted Paul Klipsch on the subject, as I recall.

As Paul said, What does it matter if you have some ohm or so of external resistance in series with 6 ohms of voice coil resistance?   

Its how output impedance affects and modifies the frequency response that we need look at. Its so obvious. That happens to be the first thing in every Stereophile test report. JA knows and he tells. Its fun to read the manufacturers response to high output impedance. They have no excuse but to make something up. 

Low damping amplifiers will bump up the bass at the resonant frequency of the speaker by providing extra voltage that is undesirable. One bump for sealed, two for ported. 

So we really aren't damping anything, are we?

@stfoth... where do these forum name  come from?

Hello, RM! You mentioned the recent measurements of the Cary SLI100. Reminds me a bit of one a few years back on the 300SEI.

https://www.stereophile.com/content/cary-audio-design-cad-300sei-integrated-amplifier-page-3

That's something of a sort of classic amp with quite a few fans.
Compound question.
Your thoughts on Dennis Had and legacy Cary gear?
Your thoughts on the disparity between the measurements and folks who say things like that in the subjective review?

I believe Dennis was a RF engineer that switched to audio. His first amp with the torroid output transformers was a quickly discontinued disaster. He should have know torroids are good for RF but no good for audio ouput. He learned though. I dont know anything about the legacy gear. Got a link?

Anyone who thinks a gapless torroid is good for an audio output transformer is kidding himself. Luckily few exist. 

Not sure i understand the second question. Can u clarify and expand?

I read a report by JA measuring a Prima Luna tube amp (some years ago). He found an output impedance of 8 ohms! This means a DF of 1 ohm or less! Combined with the typical varying impedance of most speakers this is way too high! How can supposedly competent engineers get away with something like this? Because the result is far from neutral, accurate SQ! No matter how pleasing the "golden ear" crowd claims!

@mapman 

I do not have spl measurements but will give that a shot with my cell phone over the weekend maybe and report back.

 My concern about cell phone SPL meters is how do they know the sensitivity of your microphone. Is there one specific to your phone?

You have some nice equipment, no SPL meter?:( bad bad 

Let me know when you get one. The RadioShack  is known to be quite accurate. Hope its still available. Velleman has one too I have both the digital and analog RS meters and have tested them extensively. I just use my phone to tell when BART exceeds 100 Spl. Dont trust it for more than that even though its an Iphone. 

Whats more important is to get a peak reading meter of scope and get down to business.