Likely culprit for harshness at higher volumes?

Hi folks, thanks for the continued comments.

So, if I summarize correctly, the primary suspects include:
1) speakers (distortion)
2) amplifier (insufficient to drive the KEF 4ohm load)
3) RF noise entering the lines (will get the ferrite clamps to check this out)
4) room dynamics (reflections); I walked around the room quickly and clapped in various locations. It was interesting -- even though the room is fully carpeted, I could hear reflections and a kind of pinging after each clap (I don't really know how to describe it -- a kind of reverb echo).

Oh, yea I know that the volume level reference I made above is a little abstract but I assumed that you experts would have an order of magnitude sense given the components I'm using. :) Not extremely loud but louder than conversation levels.

I'm going to try some of the easy suggestions next (this weekend):
1) using the KEF Q10's again; do a larger sample to see if perhaps my C75's are blown (but by nature, the KEFs may be subject to the distortion I'm observing in which case I may hear no difference; in this case, may need to borrow some speakers)
2) use some blankets to minimize reflectivity
3) use the ferrite clamps
4) Not sure what I can do to check if for amp insufficiency; I can try using my Nakamichi AV8 receiver but I'm assuming that the Adcom is a better amp.

Anyway, I'll start w/ #1,2,3 and go from there. I'll report back later.

Quick question on the ferrite clamps -- do I need two per channel (one at each end of the cable, so 4 altogether for a left / right pair)?

Or do I just need two for each cable pair (one at each end that wraps around both channels)?

Or do I just need one for each cable pair (one that wraps around both channels, placed either near the source or near the sink)?

I'm not sure how to use these clamps..... Thanks.

four. One each on each end of each of the cables, separate on each cable, not both cables squeezed into one ferrite.
So FOUR is the number you want to aquire.

Tsk, tsk, tsk. Twenty one posts to this thread and no one has suggested upgraded power cables? :O
Seriously though, sounds to me like speakers or room reflections are the most likely cause of your problem. You are on the right track with your 4-step program. Although I would move number 4 up to 2 and scrap number 3. Good luck and keep us informed.

Saru, why don't you at least post the city or vicinity you are located. I am sure others may be willing to stop by and listen, diagnose, and even help you ID the problem with bringing some stuff (equip, cables, deflectors, etc. . . ) over.

Any component can create congestion, HF glare, etc. . . as part of a combination with other components (or alone).

I once owned an amp (Theta Dreadnaught II) that was literally unlistenable for me. Nora Jones sounded like the worst singer in the world with that amp, any time her voice reached up it sound like she had a horrible scratchy, distorted voice. This sound only revealed itself when the amp was installed. I replaced the amp and everything went away. I once had the same issue with a DAC and another time with a CDP (but with the CDP it was only at higher volumes where it became apparent - and much less so than with the Dreadnaught).

Your steps seems to be in good order, but try to find people in your area before you start replacing components on a guessing basis. You may replace half your components before you find the real culprit if it really is even component related???