Likely culprit for harshness at higher volumes?

Its difficult to know anything by the volume references you have included. Typically, you want to report loudness in decibels (ie. 80-90-100, whatever) via the use of an SPL meter to better report how loud you are talking about. Since you like the Shack, they have them in there for pretty reasonable prices. If at some point you are going to address room issues, having even a moderately good SPL meter is very handy.

Your speakers may or may not be the cause, remember the speaker is conveying all the problems from the source on through to it. Lots of areas to pick things up and be exposed by the speakers at higher volumes.

Do a simple clap test in your room, without music on and listen for the slap echo, etc. . . a lively room will really accentuate such problems. I would do this and then address some reflectivity with items around the house for experimentation (blankets, pillows, speaker location, etc. . .

Good luck and don't start replacing too much until you at least look into the room to some degree, it could save you a fortune and lots of headaches.

Using the KEF Q10's didn't seem to make much difference; noticeable less bass but the harshness is still there, especially when a singer hits loud, high notes. Perhaps the KEF Q10's are too similar to the C75's?

I hope the Monster MC 200I-2M I'm getting next week to connect the pre-amp to the amp will make a difference.

I'll need to research what ferrite claps are -- I've never heard the term before. But sounds easy enough. I can try it w/ the current interconnects and when the Monster MC 200I-2M arrive.

Thanks for all the comments. Still open to any suggestions until the issue is solved. :)

I'll try the ferrite claps and report back later.

Hi guys,

Thanks for the good info. I connected the CD player to the pre-amp using non-brand but what seems like otherwise decent, gold plated RCA cables using the analog output/inputs. To my surprise, while the harness is still there at higher volumes, since I was listening somewhat critically, the analog actually sounded a noticeable crisper and brighter than using the toslink. The toslink sounded slightly muffled in comparison. I'll get better cables next week to connect the pre-amp to the amp; maybe the combination of using CD analog outs and better pre-amp/amp cables will help.

Anyway, the harshness is still there regardless of toslink or analog.

So, based on the comments so far, that leads to speakers and/or the room (ignoring the cables for now). I'll try using the Q10's I have and see if that makes any difference. Will report back again later.

The room is fully carpeted but the drywall walls are bare and the cabinets are either dense wood or glass so reflections are probably possible.

perhaps clipping.
Source music is awful, as has been noted by Shad, above.......look up 'loudness wars' if your want more info.

Also, Since speakers so not have watts, I'd simply ignore that rating. Good, loud, dynamic music demands a lot of an amp. Maybe it's just not passing muster.

It's your speakers.

From a review: "The overall sound can get a little grainy if pushed too hard"

I would try decent (not necessarily expensive) analog cables instead of the Toslink first.

I'm going to go out on a limb and say that it's probably your speakers or the room. The cables you describe should work just fine. I recently compared a set of $2,000 Nordost cables to a $7 pair of hardware store cables and certainly couldn't tell $1,993 worth of difference, at least for my system that I have about $5,000 in for the main stereo components. Cables make small difference and what you're describing sound like they are more significant in scale. Keep in mind that there are many members on the forum that have systems where cables might make a significant sound difference, but I don't think it applies to you and me. I'd suggest going with something like Blue Jean cables if you want something that's respected and affordable.

Saru,

It is obviously not your choice of music. I doubt it is the amp or preamp.

Therefore that leaves speakers or a jittery digital input.

One further possibility is your room, if you have tile on the floor and fairly reflective surfaces then this could be the issue - an issue that gets worse as you increase the volume.

Thanks guys.

The KEF C75 (4ohm) is rated for at least 150W I think. I think the Adcom GFA-5400 is rated for 150W/ch for 8ohm, 200W/ch for 4ohm.

I'm waiting for Monster MC 200I-2M interconnect cables (for pre-amp to amp) to arrive; hope these are okay. :) I didn't plan to change the Toslink yet. I am also planning to get some (better?) 16 gauge speaker wire from Radio Shack (I was thinking about Monster XPMS but it's 3x the price and not sure if it's any better).

The typical CD's include Jane Monheit "Never Never Land", Joe Pass "Virtuoso" and various Diane Krall; also some Burrell, Coltrane -- usual vocal/jazz stuff I guess.

I was wondering if it was the KEF's since the AVM2 and GFA-5400 seems to have good reviews. I only have KEF Q10's to try but I can see what happens. I'll also try using analog from CD to pre-amp. I was only using the digital connection because I was assuming that the AVM2 DAC's are better than the Sony's.

2 easy things to try and I'll report back later. Thanks for the help. Open for any other thoughts as well.

It could be the CD. Many modern CD's are mastered so that they sound harsh. Some genres like rock, pop and heavy metal are badly affected and virtually all recent material (as well as recent remasters of old material) can sound harsh.

You may be over-driving the speakers - the KEF75's are not known for their power handling (and can sound harsh if pushed).

Finally, it may be jitter - I doubt the AVM2 is particularly good at jitter rejection and digital interfaces very often add jitter. Try the analog output of your CD player to test this possibility.

You are either overdriving your speakers or your amp is clipping. Usually an amp issue, but I'd think the Adcom has lots of power - What is the Kef speaker power handling rating?

Or, your room needs treating for high frequencies - at higher volumes you be noticing harshness in your system that you don't at lower volumes (even though it's there).

You might look to upgrade your wires (speaker and interconnect), although I doubt that is the specific problem.