Likely culprit for harshness at higher volumes?

Your Adcom is having difficulty with transients. The poorer the recording, the more apparent this becomes. Try a really good one like say, Lyle lovett's "Natural Forces" or Jimmy Roger's "Allstars", or Ray Charles' "Genius Loves Company". A really good amp won't be limited by the recording in that it will simply reproduce what's there accurately. So if the information is diminished, it won't attenuate that upper mid-range already attenuated in the poor recording we're all familiar with as "harshness". The recording will simply be apparently "lacking". If a great recording eliminates the issue, you need to consider the perfomance of your amp. All KEFs are great speakers regardless of there particular shortcomings. If it hurts or is bothering you that much, it's the amp.

@Csontos: Thanks for the suggestion. I want to make sure I understand the methodology. The presumption is that a well recorded CD (ie - something that is well mastered using larger word sizes (24bit?) and higher sampling rates (ie - 96 or 192KHz?) and well done (ie - good recording studio, good equipment, etc) should play well on any system (up to the limits of said system).

The assumption here is that the pre-amp and speakers are not the weak link at the volumes I'm using. And even a source that is 8 or 16 bit at 48 or 96 KHz should be sufficient for a good recording to highlight deficiencies in an amp.

So, by playing a known good recording (like ones suggested), I can determine if the amp is limiting if there is harshness detected.

Whereas, if harshness isn't detected, then it's just poor recordings I'm listening to (in addition to other things like room acoustics)?

Actually, I've been wondering if there is a way to challenge each component in some way. But I've just learned that this way of thinking may not be useful -- that components play off each others strengths and weaknesses so you need to measure the system as whole in the room you are targeting. Must drive audio component retailers crazy - a component that sounds good in the store may sound lacking at home :)

So, if I learn that the Adcom is lacking, I guess that's what the amp forum is for. :)

That's just it. It's not the good one that reveals the amp's true potential nearly as much as the poor one. The amp is the heart of the system. Once you've gotten used to the attributes of your other gear, you then begin listening to, guess what?... your amp, "again". The component you get used to the quickest is believe it or not actually the weakest link, your speakers. What you will never get used to are the shortcomings of your amp because they are constantly being revealed and so become your focus. For the amp to "disappear", it needs 3 attributes relative to your ears; it has to be "fast", it has to have a truly flat frequency response- one that is not can seriously contribute to the harshness you're talking about, and it must be very linear. Whatever other attributes it has are a bonus A truly high-end amp is probably the one that leaves you scratching your head wondering what makes it a high-end amp because it's so "flat and dry". Everyone out there building amps is applying their own brand of "voo-doo" in order to compete with each other. What I mean by that is it's easy to show a flat response on a 6 inch tape. Stretch it out 3 feet and you'll see just how flat it really is! It's not possible to add without subtracting, and they're all doing it fooling you into thinking you're getting a superior product. It's usually located in the bottom end and/or upper mid-range- it being the most bothersome since it thickens transients in the vocal range which can be fatiguing or downright ear-piercing. At first it's an up front in your face soundstage but then begins to take it's toll on your ears with lots of missing depth. Poor recordings should simply sound as they should.."lacking". They should not be ear-piercing or irritating at all! Remember, the entire system is nothing but a playback device. If the components are of sufficient quality and functioning properly, "revealing" poorly embedded information should sound as smooth and clear in terms of what's there, as the opposite. It doesn't "improve" it, but just plays it back.DC offset problems and bias issues can definitely cause the problem you are experiencing. Are both channels the same temperature within a couple of degrees? Have you checked the offset? These factors can ruin the sound of an otherwise great amp.

Hi all,

If anyone is still reading this, I was wondering if I might ask one closing question.

I've been reading up on jitter (who knew moving to digital wasn't going to be perfect?). I don't have a detailed understanding but I do have some questions about how it manifests itself:

1) when it happens, I assume it's not modulated by volume levels. I should observe equally at low and high volumes although it might be more obvious at higher volumes. Correct?

2) when it happens, does it happen just for a brief period (milliseconds? seconds?)? Or does it happen almost continuously? If it happens, does it just happen once and go away for awhile? Or will it happen frequently?

3) is coax and optical equally susceptible? or is one better than the other? In any case, it sounds like analog between the source and pre-amp is the way to go. So, this suggests I should focus on having a good DAC and electronics in the source and should not care what is inside the pre-amp / processor. Correct?

Thanks again to all for your help. My modest system is not perfect but it's much more enjoyable now than before.

@Csontos: Thanks for the explanation. I think I get the high level gist although I'll have to research more about the 3 attributes: fast, flat, linear. Not sure what the standard metrics are for these attributes, what range of values is considered acceptable, and make/model/costs associated with various ranges. I'll try to research my unit to form a baseline.

I measured, using an infrared meter, the top cover vents of the amp and left and right seem to be fairly close (91 degrees +- a couple degrees) while playing Monheit). I don't know what offset is and how to check / adjust it. Is that something available on all amps (nothing mentioned in my manual that I recall). Or only 'good' ones?