Help with buzz / hum that's making me insane r

I've recently realized that there's a very very subtle buzz or hum coming from the dome tweeters of BOTH of my Dali's that's audible if my ears are right next to them. Now before everyone says the tweeters are blown, let me take you through what I've done to analyze the situation (it could also be that I'm crazy):

Hooked up Dali's to a different amp using same front end, still hum
Hooked up different speakers to amp/front end, still hum
Swapped around ICs (I'm running balanced on DAC and Phono), still hum
Rewired system making sure PCs and ICs aren't touching, still hum
Hum is present with both vinyl and digital

The sound is still very, very good, but I can't help feel like on higher register vocals I can hear just a touch of distortion that I wasn't hearing before. Again, this is on both channels, and the sound is great, but vocals and highs have a small touch of rasp. I can't tell if this is me being crazy, because I can hear the hum from the dome tweeters when my ear is right next to them. Any ideas of ways to play around to see what the problem is.

I'm using shunyata PCs for the most part (one cardas) and a Hydra 6 into a Shunyata outlet. Help is greatly appreciated, as this is driving me nuts
Usually this is an indication of a ground loop especially when no video equipment is connected. Try lifting the grounds to source components or disconnect all from amp and reconnect one at a time to isolate the problem. Power down amp while reconnecting to avoid problems.

When I connected the Shunyata wall outlet I noticed the ground had been floated, so I reconnected it to the shunyata outlet. I'm fairly new at the idea of playing around with power, so am I correct in thinking you mean I should remove the ground (green wire) from the shunyata duplex? I was told this was dangerous, so if you or anyone can chime in, that would be great.I may be misunderstanding what you mean by "lifting the ground", in which case I'd be grateful if you could let me know how to do this. I do have video equipment connected, but powered it down and disconnected from mains and that didn't do it either.
Try disconnecting all TV inputs and outputs - cable, satellite, antenna, HDMI, coax, eveything. If that eliminates the hum, starting reconnecting one at a time until the hum comes back.
Is it a hum (ground loop issue), buzz, or hiss from your tweeters?

Some hiss from tweeters may be normal when you put your ear right up to the tweeter. Buzz or crackling is another story.
If you have any low voltage halogen lighting this will produce a slight buzzing
The hum is most likely the suggested ground loop and the way the electrical panel was grounded
There are a few things I would look for.
- Is there a light dimmer on the circuit or on a neighboring circuit? If so disconnect and see if problem stops.

- Are all your connections tight in the breaker box? They come loose with time and vibrate and cause noise. It was amazing the improvement I had after tightening all the screw terminals. (Eliminating hf microphonic vibration).

Do NOT bypass the ground with cheater plugs. This is a safety issue.
What you describe is normal.

If you have to be that close to hear it you do not have a problem.

Thanks everyone for your responses.

Sonofnorway: the only interaction between my video and audio setup is I have the audio of cable going through the integrated with a humbuster rca pair. I disconnected the that rca pair and unplugged all the power of the video setup (plasma screen, brain, cable and dvd) from the wall and the hiss was still there. I didn't unplug the cable from the cable box, but there was no power going to any of the video gear and they weren't linked to audio setup with any ICs.

Nick778: thanks for the clarifying question. It's definitely a hiss that also has a very slight fizz to it, like a digital hiss. It's only on the dome tweeters of the Dali's; the ribbon tweeter and other drivers are dead silent.

Apachef1: On the same circuit I have my NAS for my media server, a Cable modem, a printer, a phone and two lamps, both non-halogen. All kitchen appliances (fridge etc) are on a different line. (I can't install dedicated lines, FWIW).

Hififile: No dimmers, but kitchen apps are on a neighboring circuit. It's a condo in 50-unit building. I don't think my breaker box has any screws to tighten--it's all just breakers w/switches, but I'll check.

Herman: The only problem is that this is a new thing I'm experiencing. The hiss may have been there all along and I'm just now noticing it, but the way it manifests itself in listening is that vocalists with higher-pitched voices, or violins, etc have a very, very subtle distortion. So, vocals that seem to me like they should be crystal clear in production (annie lenox, etc) have a very slight throatiness to them. In most cases this just sounds like texture to me, but sometimes sounds like distortion. Again, it's very subtle and it could be that all the upgrades have made my system more revealing and I'm hearing things I wasn't before that sound like slight distortion but are just texture; however, I'm perplexed and do want to get to the bottom of this. I notice this more on voices in the middle of the soundstage. All other frequencies sound frigging amazing, and not all treble sounds this way, so it could be psychosomatic, but I would like to figure out if there's an issue or I need to adjust to my system. Sure I'm not the first!
There are few amps that don't produce the hiss you describe if you are talking about getting your ear within six inches or less. The more efficient your speakers the more noticeable the hiss.
There are two amps which come to mind that were dead quiet, the Acurus A-200 and Sony TA-F707es. A noisy amp that comes to mind was the Portal Panache. It hummed and hissed and also produced an annoying thump during power on/off. The odd thing is the Portal was one of the best sounding amps I've owned once the music started.
The amp is dead silent. I just disconnected everything, save the amp and threw the breakers on the rest of the house and the hiss was still there. Then plugged in sources one by one, then added video section--still hiss. Then powered up rest of house--still hiss.

The hiss is only audible with ear next to speaker (the same was the case when I connected different speakers, so it's not the speaker, and the hiss was there with different amp, so it's not the amp).

I'm realizing I may be a big huge idiot. My wife feels, and she has very good ears, that this is just a more revealing system then any I've had, so voices actually have texture, as opposed to always sounding pristine. I can't imagine it's a ground loop, since I've disconnected everything and the sound is still there. The sound of my system is amazing, so maybe I'm trying to hear something that isn't there, which may be true because I don't notice it on all recordings. Can this hobby drive you crazy or what! If others can chime in as having experience this, or it being normal (as has happened in this thread) then maybe I need to trust that advice.
The hiss with your ear next to the dome tweeters means they are working. Agree with Herman it's not a malfunction. Advise you not increase the volume above normal listening levels to listen only to the hiss.

You can lift ground by adding a two prong cheater to the end of a three prong plug. So long as one component is properly grounded all the others linked via interconnects will share that ground. That's why if you did have hum, which sounds like you do not, the hum will persist even if the offending units are turned off but remain connected.

Dissatisfaction with the system's sound indeed indicates distortion. Surely it has nothing to do with your operating dome tweeters.

Enjoy that pretty room you have but move the carpet over so it's centralized equally between your speakers.
Thanks Rockvirgo, I am moving the carpet tomorrow. Can't believe I never picked up on it. I have been, and am still VERY happy with my system; however, in thinking about my hiss issue, I've decided there are two separate things going on:

1) The tweeter hiss is perfectly normal and only audible if ear is at tweeter
2) I could have a sibilance issue do to recabling and adding new ICs

Assuming the sibilance is cable related, I guess I'm wondering what to do. I didn't notice it before installing the Nordost cables, so I will swap them out and see if that is the issue, although I'd be surprised (wouldn't be the first time). If that's not it, I'm wondering what my next step should be. My speaker cables are 3 meters, which is more than I need, so I've got the excess length coiled under my stand. I had them this way before the sibilance became an issue, although I did recently remove them and put them back in, and I know purist cables are thought to take a while to settle back in, so maybe it's just a waiting game.

If it's not the SCs and not the ICs, then what next? From reading other descriptions of this sibilance issue from other people on the net who've experienced it, I'm pretty sure that's what's going on.

Should I clean my connectors? cap off any unused inputs on my integrated?
Fold the excess speaker cable concertina style (like an accordian) back and forth like a sine wave instead of round and round. Coiled wire behaves like an antenna or motor or something. Best of luck finding the sibilance.
Don't feel stupid, feel like you learned something.

Could it perhaps be the recordings, I believe you mentioned it doesn't happen on all and it could well be that a particular recording is overloaded. Can you compare one of those recordings on another good system?
That's what I'm going to do this weekend hopefully. I talked with Grant from Shunyata who was extremely helpful and am going to test out some other things as well. I gotta say, I am blown away by how much time Grant spent with me, and how insightful he was. Excellent customer service.
Which recordings are you hearing this on? If you could be specific about what you hearing on a particular point in the song I'm sure somebody hear has the same recording and could chime in on what they hear.
Now that the issue is sibilance, I'm wondering if it is associated mainly with the phono and if so also with certain records?

For reference, I detect a sibilance issue most easily by listening to recordings where vocalists, particularly female, pronounce the letter 's'. If the sound is raspy or edgy sounding and not perfectly smooth, then there is sibilance.

Sibilance with the phono is often a result of cartridge misalignment and/or dirt deposits on the stylus (which can be removed easily with a stylus brush) and/or stylus wear or damage.

If it happens with some records and not others, then it is mostly likely record wear or perhaps dirt on those specific records.

If its in the digital source as well, then perhaps there is a loose or poor connection between components or level mismatch issue between components (check component input/out put specs in manuals, if available) or a technical problem within one or more components.

The best way to find a subtle issue like this within a component if it exists is to switch that component in/out of the system with a spare replacement component in good working order, if possible, and see if the issue goes away. Trial and error is involved here.
Thanks mapman. It's on digital and vinyl. My theory, which I'll be testing this weekend, is that it's a cabling issue. I didn't have this issue prior to taking my system apart and reinstalling it in a different configuration. A number of people (grant from Shunyata included) said that this may dissipate over time as things settle back in, and could also be because I have my 3 meter purist Speaker cables coiled around eachother under my rack, which is stupid. I'm going to change that this weekend, clean all contacts and plug any unused inputs/outputs and then see what happens. If that doesn't do it, then I will start at the very beginning and do a methodical sweep of the system to isolate it, bringing in a different amp if necessary.
Sounds like a plan.

Only thing else I can think of to be alert to is some recordings may have natural sibilance baked into them for various reasons relating to the production. Just be certain that the recordings you test with are not naturally sibilant. If its happening consistently from recording to recording, however, this is probably not the case.

Good luck!
If you have a copy of Holly Cole's "Blame It On My Youth," the first cut has an excellent song to test sibilance. She sings "slip into silent slumber, sail on a silver mist, slowly but surely your senses will cease to exist." What a line for sibilance. On my current system there is no sibilance issue with this cut. But I have noted problems with other pieces of gear.
I'm going to post my results from my experiments to solve this issue, that way it could maybe be useful for someone else who finds themselves in the same predicament.

I've thoroughly tested all equipment, bringing in alternate pieces when necessary (speakers, integrated amp and cd player in place of media server) and the issue doesn't change, so it's not the usual suspects (amp, source or speaker). I shut off the breakers to the rest of the house and verified it's not an appliance on another line. I've tried a variety of recordings to make sure it's not just an issue with one recording.

Following the advice of Grant from Shunyata I uncoiled my speaker cables and ran them straighter, without any coils to the speakers and let them settle back down. This was the first thing to have positive sonic results in my experiment. Sibilance isn't gone altogether, but treble sounds more open with zero distortion. Playing Marie Laveau from Kenny Barron's "Things Unseen" Album, the trumpet sounds still a little piercing, with sibilance on highly extended passages, but better than it before. Then, I took out my Nordost IC and took it over to my dad's to test it out in his system (this is the newest cable I added) thinking maybe something was up with it, but it sounds frigging amazing. I bring it back home and do an A/B with the purist IC and sure enough, the sibilance is only noticeable on recordings like the kenny barron that less than stellar trumpet production work (IMO). So I think it comes down to the Nordost being a bad match for the Dali's. When I first put it in, I was really in love with it, and I'm feeling a bit foolish for being so quick to jump up and down for joy. I think the Dali's are just too forward for the Nordost, which is a bummer because I love this cable. In any case, I still plan on doing a connector cleaning and further isolation tests to make sure, but I'm heaving a pretty big sigh of relief.

Thanks everyone for your help.