How am I frying all my amps? Oscillating? Help

Hi. So I'm on my third amp this year.

I had an Adcom GFA-7000 for many years which I gave to a buddy for his birthday so I could get a Krell. The Adcom used to "hum" or "buzz" for five minutes then stop, then start again a few hours later. It wasn't noticeable with the music playing. Also, when nothing was playing, it would pop and hiss when the volume was turned all the way up as if the volume control was directly connected to the speakers and was shorting them or something. It ran for nine years and is still going strong today. It did none of these things when I first got it.

Then I got a Krell KAV-500. There was always something wrong with this amp because it wouldn't turn on when I first got it. Then it did turn on and I used it and it would hum like the Adcom and its volume control noises were even worse. Then it exploded and got sent to Krell for repair (still not back). Also, the Krell would make a horrible buzzing sound when only RCAs or XLRs were plugged into it, no speaker wire (and I tried a dozen different cables as it took only one to reproduce the problem). And when you muted or turned off the pre-amp, the thing would send a horribly loud buzz through the speakers. It did not do this when I first got it.

So I got a Classe CA-200. This amp was dead quiet and had zero problems. Two nights ago I noticed the volume control was being noisy. Last night I noticed the amp hum. So I looked around, and of course, now the thing exhibits all the same traits of the Krell except quieter: volume control noise, buzz when the pre-amp is off or muted, buzz with only ICs connected. I expect it will get louder until it blows up as per the Krell.

My system has changed dramatically between the three amps. There are two commonalities for all of them: Goertz MI2 Veracity Cu speaker cable and Thiel CS1.5 speakers. The Zobels are on the speakers ends of the Goertz cable.

In addition to the speakers and wire, the Krell and Classe have two more in common items: Cary Cinema 11 preamp and PS Audio Ultimate Outlet.

The Adcom never really died. The Krell and Classe look like its going to take about two months each but I find it difficult to believe a Line Conditioner or Preamp can cause this kind of damage. That leaves me to think they are oscillating due to the Goertz cable but I don't know nearly enough about it for this to be anything but an uneducated guess.

I leave everything on all the time. What am I doing to my amps? :-(

Probably obvious, but did you try plugging amps into different sockets? If all amps developed problems from the same sockets, maybe something is wired incorrectly or there is a fault someplace.
Just to be certain you've isolated suspect socket run, try an extension cord from a completely different run.
It is odd that 3 amps developed trouble.
Also, remove the line conditioner for a while and see what happens.
Another consideration is- for the price of a new amp and line conditioner, you could have an electrician run dedicated lines to your room.
Just ideas. Hope they help.
The Adcom was plugged directly into the wall. The Krell was plugged into the wall for half its life. Can't see what a functioning line conditioner can do to an amp, either its getting non-shorted power of the right voltage or not, right? And I ran my own dedicated lines, three in fact, though I'm only using two currently.

Oregon, what in the power system could slowly fry an amp except for under/over voltage which would affect everything else in my house too?
A simple test of the outlet would tell you if there were an AC problem. From your description, it really sounds like the AC supply would be the first place to look.
You may have the polarity reversed in your wall socket. Even though the plug only fits one way, the wires may be switched (i.e. hot wire on neutral screw and vice-versa). If so, that can definitely fry capacitors in your amps. Have an electrician check it out ASAP.
Don't know about your speaker cables, but some designs do cause ossilations in an amp. Remove your present cables and try some old fashion 12 guage copper cables and see if that solves your problem. If so, you can then simply refocus your attention on proper cables.
Honestly, I know nothing about electricity. To me, it's black magic. All I know is rain.
But, my feeling is if you can simply use different outlets and the amps behave themselves, this is simplest test. Be certain it is a completely separate run of course. This won't cost you any $. Normally, I'd say this is a very, very long shot.
However, since you now say that YOU ran some dedicated lines (especially if it were ME who ran the lines), then why not double check them by using my experiment? Cheap, won't hurt.
A line conditioner could be bad as well. If the same conditioner was in the loop with the Adcom, Classe and Krell, it might have been damaged, now defective.
These are all uneducated, wild, off the handle guesses.
I used conditioners and power surge protectors for a bout a month many years ago. I feel they have no value, just make things more complicated and may even poorly affect the sound. But that's just my opinion.
Luckily, here in stormy Oregon, I have not had a surge.
All these power conditioner things are hokus-pokus.
Also, i turn my equipment off whenever I'm not listening.
These are my srewy, rain sogged opinions.
Tobias, what is this simple test of an outlet?

I just broke out my Fluke MM. The voltage at the wall is 123.0. The voltage at the power cord to the UO is 123.0. The voltage at the outlet end of the UO is 123.0. The voltage at the power cord to the amp is 123.0. Both UPSes in the computer room report 123.0.

What else is there to look at please? What principle of electricity in physics that isn't voltage can cause this anyway?

Newbee, if I swap in some lamp cord, how will I know the problem is gone? These amps aren't even supposed to be susceptible to oscillation from what I understood and the Zobels are there but I too seem to think this is where I should be looking.
Ait, just plugged the polarity checker into the wall outlet and the UO outlet. Reports polarity correct. I've wired my entire house and numerous others and been through state inspections. We can call me an electrician.
FWIW, as I recall the speaker cable types than can typically cause osscillations in an amp are those which have widely spaced positive and negative wires. I suggest that you take a few moments and do some research on this issue in Google - there are a lot of articles on this subject, which discuss the issues involved and which may have some application to your system. Other that a little time you've nothing to lose, and might gain a better appreciation for the terms 'inductance', 'resistence', and 'capacitance' and how they interface.

Re your question about 'what should I hear', the answer is nothing at all. Whether cheap 12ga cord sounds good to you or not what it will not introduce is the problems you have described. For test purposes, and actually some fairly good sound, I would recommend some 11 ga Canare Star 4S11. I use it regularily and I consider it a great bargin in non-exotic copper cable and I have used it regularily.

Hope that helps a bit.
Newbee, thats the other way around. Goertz cable causes oscillation because the wires are so closely spaced together that they have very high capacitance. Still, this should be an issue with Zobels and these particular amps from what I know.

Maybe the Zobels came loose? Hmmm.
Mental note--never let Leoturetsky borrow my gear...

You mention Zobel networks on the end of your speaker cables. Have you removed them and has it reduced any of the pops/noises? Just a guess, but I beleive the Zobels change the load on the amp, which seems to be the damaged items
In regards to the power; A loose wire connection, wire nut or frayed wires could enable the power meter to still read 123.0 volts BUT not allow enough emperage through. Your meter only needs a fraction of an amp to read. You amps could pull a lot more amps when powering up or cranking them up. If this is the case, when the amps are trying to pull more amperage through poor wiring, say for instance only one or 2 strands are allowing the juice through, the voltage may drop down considerably to even 40 or 50 volts. That could fry the heck out of them. Just a thought worth checking out. Good luck! -John
There maybe a short in the speakers crossover, preamp could be putting out DC. I'd also can the goertz cable. Certainly don't hook up the repaied amps until you find the problem.
Yep, I think you are right about the appearance/design of the cable causing (or not) high(er)capacitance. My fading memory of problems not personally encountered. I read a lot of stuff but have zero retension skills. But, I think I did get you to the right church, now you just need to find the right pew. Zobels or not. :-)

I still think you should take out the Goertz and Zobels and see what happens. Challenge your assumptions and let me know what you discover. I'm curious.
A preamp can, in fact, cause that kind of damage if its DC blocking caps are not doing their job. I think your amps are being slowly poisoned by DC, whether it's from the preamp or the wall socket.
Leoturetsky, how did you wind up with such an eclectic bunch of gear? Get a good integrated amp with a top quality PC from Transparent or MIT for line filtration. Use a decent CDP and well designed cables that work well with any components and reduce noise in your system such as MIT. For God's sake get rid of the Zobel networks and the Goertz cables (excellent for pulling in VHF but horrible for audio). Thiel speakers aren't exactly music makers either. Power strips and ultimate outlets are worthless as well...keep the krell amp maybe and get a krell 280p or older ARC LS15 preamp for starts and some MIT shotgun cables. Cary Cinema preamp?? Really now.
GS5556, You have a good point. I fried an amp (and subsequently a tweeter) with DC from a tube amp into a SS amp w/out transformers (contrarty to the pre-amp designers intention). I'm so provincial, I'm not familar with his stuff and I just assumed that the poster was using integraded amps. Oh well - but FWIW when my amp went down it did so quietly, no pops, burps, or noise whatsoever. Would that be typical?
Leoturetsky, the "simple test" I was referring to is basically what you have done: voltage and polarity. My idea of anything more sophisticated would involve an oscilloscope and a check of the AC waveform. Maybe you should do that if you have any doubt that the AC wave may be sinusoidal. Otherwise, not.

Next step would be to check the preamp's output and the integrity of your speaker cables. I have real trouble imagining that even the reviled-by-some Goertz cables would cause what you describe unless they (or the connectors) were damaged--partially shorted, for example.

If you were looking for an alternative (and cheap) speaker cable for a swap test, though, I would second Newbee's recommendation of Canare QuadStar 4S11.
Reb1208, Gs5556, can you explain how DC from the pre affects the amp? Why would the amp care what signal it amplifies? I'm not arguing, just not understanding.

Gs5556, how does DC come from the wall socket? Or do you mean the UO?

Jsd52756, the lines from the wall to the outlet are Romex, no issues there. The PC on the Classe is a brand new PS Audio molded cord that has never been used anywhere else so I can't imagine it can be a problem. The PC to the UO is a Belden 83803 cord I made myself and I've used it without issue in multiple other places. Also, wouldn't the low amperage you describe be an audible problem? The Thiels would have VERY harsh treble without enough juice, no?

Justlisten, no kidding, huh? I don't even want to put more gear in my system and I have the money for an SACD player ready to go. :-(

Tobias, how do I check the preamp's output? I don't even have a guess here. And the AC is a sine wave... I have graphed it for kicks before. :-)

Dave_b, we're you being helpful, insulting, humorous, or stupid? I totally missed anything useful in your entire post.
Just trying to point out that somtimes one can be completely unaware of the obvious while looking toward the obscure for an answer. Adding extra networks across your speaker terminals in front of speaker cables that would be better served pulling in tv channels is naive at best. System synergy is also very important and seems to be lacking in your choice of gear. Quality gear and great cables will avoid a multitude of potential mismatches.
My guess goes to the goertz cables being the culprit. I was wondering if you had goertz cables even before I read through. I had the same cables on an electrocompaniet eci3 integrated amp. The amp started shutting down a few months after i bought the amp. my dealer even gave me a new eci3 as they couldn't figure out the problem. The goertz cables causing problems with amps wasn't common knowledge at the time. Anyway, I figured out it was the cables, because, I had the new amp on, with the cables, but no speakers connected, and the amp shut off. I changed the cables, no more problems with that amp. I think it was 4 years later that goertz started putting the zobel network on their cables.
Hi, I have a Classe amp, very similar to yours, of the same series. The Classe has a protection circuit that shuts it down (flashes green) if it senses any DC from the preamp. With my tube preamp, I have to turn the Classe on last, and off first, or it will not work. My Classe also dislikes my PS audio ps-200, which is basically two Ultimate Outlets in one box. From experience, I never use a power conditioner with any big solid state amp. Your PS audio ultimate outlet, however, will do wonders for the Cary Cinema 11,and your CD player, particularly in keeping the noise from the Cary's built in DAC OUT of the other gear.

I would seriously doubt if the Goertz cables were to blame,as these amps can drive any cables; or the UO were at fault(a passive balun type isolation device, I believe). The amps you are losing are extremely reliable. I really would plug the amp straight into the wall, and borrow a different preamp. I suspect your Cary needs service, it appears to be a very complex unit. Volume control noises are the fault of the preamp, not the amps, they just amplify what they receive, in this case a noisy, dirty, possibly shorted volume control.
If the Goertz Alpha-Core RC networks were damaged it might explain the oscillating on some amps, but that the oscillating also happened with the Krell amps which don't require the RC networks, leads me to believe the problem is elsewhere.
Who built the Zobel networks? I have heard that these can cause problems when improperly designed/implemented.
If not the Zobels,then look at the pre-a trip back to Cary??
Alright, I guess the Cary goes to the dealer. And I'll pull the Goertz temporarily as well.

Don't you guys think the Classe is already shot? Or will it recover because its own protection circuitry says nothing is wrong?

Dave_b, how does a guy with MIT and Transparent cabling tell anyone not to add extra networks in front of their speakers? Is your Zobel better than mine?
Leoturetsky, I am surprised that the term 'RF' has not arisen before now! You are describing classic RF interference issues.

I doubt very much that the Goertz cable is responsible for oscillation in three different amps. A speaker cable that can cause oscillation?? Really, an amp has to be pretty unstable for this to be an issue and the amps you mention don't have the reputation for that. So I will use Occam's razor and go for the simple explanation: its not the cable, you have an RF problem.

Digital equipment by their very nature are RF generators. If the designer has done his homework, then this is usually not a problem, but a malfunction can throw out all bets. I would not be trusting of the PS Audio until this matter is resolve either.

So, I have a test for you. Plug the amp directly into the wall. MAKE SURE that the PS Audio is not plugged into anything. Also MAKE SURE that your digital equipment is completely unplugged too. For that matter, let's make sure that the amp itself is the only thing that is plugged into the wall. Does it still behave the same way??

No, its OK= the cable is fine and you have a malfunction in something other than your amp.

Yes, its the same= we still don't know its your cable or not, but it **isn't** your associated equipment.

The next thing I would do is look for RF sources. How many feet are you from that AM/FM?TV broadcast station tower? Can you see if from your house? Have you ever heard garbled radio programming on your amp at any time since this issue arose or before that? If you have RF from outside the house there are things that you can do. But let's answer the initial questions above with the test I gave you first.

I bet the RF problem is the digital Cary Pre-amp:

From the owners manuel

All of the Main Room audio output connectors have 24-bit/192 kHz D/A converters operating in
dual differential mode for excellent sound quality and high dynamic range. In addition, the
Cinema 11 includes 7.1 channel XLR balanced audio outputs for your main listening room if you
are using a power amplifier with balanced input connections.
The Cinema 11 is designed to remain viable in a future of rapidly emerging digital technologies.
It has a rear panel RS-232 serial port connector provided for home automation serial control and
allows us to perform flash-memory software upgrades with this connection. We have added an
unusual looking 'system link' connector to support digital future expansion for high definition
audio codecs included with the new higher definition video disks now being sold. The system link
connector is available for future new surround modes like Dolby True HD and DTS-HD, making it
possible to more than quadruple the Cinema 11’s tremendous processing power. This connector
is originally from the computer industry and features frequency bandwidth capabilities exceeding
2 gHz! We will make an adapter for video processing to access this connector and offer high
performance video switching and scaling to our users.
Atmasphere, I had done these tests with the Krell before it exploded and I did the same tests with the Classe just now with equivalent results.

The scenario:
1) Amp plugged into wall. I tried all three dedicated circuits.
2) Nothing is plugged in except the amp.
3) Speakers are connected to the amp with my Goertz cabling.
4) No connections between amp and other gear (which isn't on anyway).
5) Plug in one XLR or RCA cable to the amp.

My home:
1) In the boonies.
2) I used to have a satellite exception because I can't pick up local channels via an antennae without serious ghosting. The local FOX, ABC, and NBC affiliates were all at my house to confirm this (CBS gave in without a fight).
3) My cell phone only gets service on the top deck of the pool and then only on certain days.
4) There is a power transformer with a sodium vapor light about 700 feet down hill from me and it seems the electric company repairs things there every time the power goes out.
5) I have a power line on a right-of-way about 100 feet behind my listening room but its one power line running to the six houses behind me, not a distribution center with 75' towers.
6) I have never heard any crosstalk on anything and cannot see any towers around me from my house.

The result:
1) A quiet but high pitched squeal through the speaker when no ICs are connected. Its definitely abnormal and isn't there when the preamp is on.
2) Using XLO or MicroPurl ICs, ie not shielded, if you move, wiggle, or rub ANY part of the IC on ANYTHING, you get static and white noise in addition to the quiet, high pitched squeal.
3) Try an AudioQuest IC, ie shielded cable, the squeal is still there but rubbing the cable against the rack doesn't produce extra noise and there is no static.
4) Wrapping either RCA end with my hand, without touching the middle plug, eliminates all the noise, including the squeal, on the AQ and MP but only gets rid of the static with the XLO.

Interference kind of makes more sense to me too. Hadn't even occurred to me. And since I know something was already wrong with the Krell when I got it, that would explain why all three amps have the same symptoms but why one amp actually died.

AND it would make me feel better... or is that because I don't know enough about it?
Leoturetsky, checking the preamp's output is a job for a technician unless you yourself know how to input a test signal and read the output for distortion. I would put it on the list for later and go with Atmasphere's advice for the present. It sounds from recent posts as though RF needs to be eliminated as the problem first.

That said, two things occur to me. It would be interesting to hear from Krell about the condition of your old amp. And... I know Atmasphere (who should know if anyone would) is skeptical about the influence of your speaker cables. I too find it hard to imagine (putting myself in rather good company), but all the same I would try swapping in something different just for a check. Maybe even zip cord.

This is a fascinating problem. Thanks and keep posting!
Tobias, if I has an oscilloscope I would test the pre. One of my customers has dozens of them but I don't know if he'd let me borrow one.

I would be most interested to hear from Krell now too. They've had the amp for three weeks and only promised to get started looking at it next week. Thats after I had to call one of the D'Agostino's themselves since no one else in their entire phone directory (!!!) would pick up the phone or answer email over almost two weeks time!
Leoturetsky, OK- I'm convinced that the RF is not from a radio station or the like. In your testing above, was the digital system plugged into the wall even though it was not connected to the amp?

I would indeed try a set of zip cord or similar speaker wires just so we can put the speaker cable thing to bed.

XLO is an example of unshielded wire; it doesn't surprise me in the least that you have hum problems with that! In fact, with the further description you have provided, it sounds more like a ground loop or bad grounding in general.

If you have a preamp/power amp: the preamp should be the system central ground. All other components (sources and amplifier) should 'float' that is, not be grounded. They should get their ground through the interconnect cable.

If you have an integrated amp, it should be properly grounded, and your sources should float.

I would avoid using power line conditioners until you have the ground thing sorted out. Sometimes they can create confusion when chasing things like this.
Atmasphere, no other components were plugged in during my testing, digital or otherwise. Just the amp. So it can't be a ground loop, right?

I've had a ground loop before. It sounded like a loud hum/buzz. The noise I'm getting is a "wavy/wiggly" squeal like a hundred of mice talking at once. It doesn't sound like any crosstalk I've heard before though.

A bad ground, eh? Another member on this site asked if I would like him to check it out (he's a professional electrician) but I didn't want to bother him (particularly for free) if we couldn't get this narrowed down better. When you say "bad ground" you mean at the electrical box not the wall outlet, right? That wouldn't surprise me I guess since I did redo all of the wiring in this house for a reason, but, would I not have some kind of effect from a bad ground in other appliances of my house? Shouldn't air conditioner compressors go bad quickly?

I can add cheater plugs but if the problem exists with one component the answer has to be elsewhere, right?
Leoturetsky, in this we have narrowed it down substantially. I'll be surprised if it is the speaker cable, but I would not let that stop me from trying a different one.

If the cable has no effect, the simple fact is you have had a run of bad luck, or you have a lot of mice :)
If you have DC on your preamp output couldn't you measure it with a voltmeter? Seems to me the output of a preamp should measure 0VDC when measuring with a voltmeter at any volume level. If there is DC present, the output caps in the preamp are bad.
Joeylawn36111, You are correct. A tech just had me measure my preamplifier using a multimeter set at V-DC 200m with everything powered on but no music playing. I measured at the speaker binding posts. I believe that is SOP but hopefully someone else will verify that.
If you suspect the preamp has DC at its output, that is where you should measure for it. Some amplifiers have an input coupling cap and many don't so there is no guarantee that you will read DC at the output of the amp just because there is DC at the input.

In addition, many solid state amplifiers have a DC output protection circuit, which will prevent the amp from running if DC is present. So you may not be able to read DC at the output for that reason either.
OOOOPS, I typed "preamplifier" when I meant to type "amplifier". I was checking the amplifier, not the preamplifier. It was an amplifier/speaker issue I was working on.

My point was even if someone can't type, they can check DC witha multimeter.
I will check for DC at the preamp on Sunday. How does one measure an XLR output? Both pins, one at a time, to ground?

Atmasphere, I'm confused as to what your final opinion is on whats wrong?

Thank you everyone!
I happened to come across this thread and found something interesting. I've also recently been having some problems with my equipment; two different sets of tube amps developed a problem which then had to be sent back for repair. One channel of one of the sets ended up having a bunch of burned capacitors, resistors, and a bias trim pot. I just received a brand new set of tube amps, and one of the amps has a problem right off the bat, although it would be hard for me to believe that something in my system caused that to happen immediately.

The interesting thing?: I am also using Goertz MI2 Veracity Cu speaker cables. The problems only happened after I started using these cables, which was a couple of months ago. Could the cables really cause these problems, or is it just a coincidence?
"The interesting thing?: I am also using Goertz MI2 Veracity Cu speaker cables. The problems only happened after I started using these cables, which was a couple of months ago. Could the cables really cause these problems, or is it just a coincidence?"

I'd sure hate to find out for myself, but the cable sure is suspect now. If the cable is the cause, not only could the amp be damaged but the passives in the x-over can short out.
The Alpha-Core Goertz speaker cables shouldn't cause problems with most amplifiers, but I strongly suggest the use of the Alpha-Core RC networks or similar zobel networks to be sure!
"The Alpha-Core Goertz speaker cables shouldn't cause problems with most amplifiers, but I strongly suggest the use of the Alpha-Core RC networks or similar zobel networks to be sure!"

Why? What are these networks supposed to do?
The networks keep wide bandwidth amplifiers from oscillating.
You wrote:
A quiet but high pitched squeal through the speaker when no ICs are connected. Its definitely abnormal and isn't there when the preamp is on.
**THIS IS NORMAL One should never power up a high-powr amp with no ground connection thru the ICs.

2) Using XLO or MicroPurl ICs, ie not shielded, if you move, wiggle, or rub ANY part of the IC on ANYTHING, you get static and white noise in addition to the quiet, high pitched squeal.

3) Try an AudioQuest IC, ie shielded cable, the squeal is still there but rubbing the cable against the rack doesn't produce extra noise and there is no static.

4) Wrapping either RCA end with my hand, without touching the middle plug, eliminates all the noise, including the squeal, on the AQ and MP but only gets rid of the static with the XLO."
DITTO, NORMAL.Your hand "shields" the spurious signal.

NEVER test a high power amp with an open input (open-ended ICs are an open input plus a long antenna to pick-up noise).

My suggestion: buy a pair of inexpensive Radio Schack RCA connectors; short positive to negative on those RCAs by bending the metal parts.
Connect the shorted RCAs to the amplifier input and measure DC mV across the amp's speaker outputs. If the DMM reading is close to zero, the amp is fine.
To double check, measure AC V (lowest range on your DMM), it should be zero.

Power down the amp and move the shorted RCA's to the preamp input and measure DC mv across the preamp's outputs. Use an RCA output to make it simpler: the external contact is minus, the center pin is plus. Adjust the volume control up and down. If the meter shows an up and down DC reading, your preamp is defective (DC on the output). If the DMM reads zero no matter how you move the volume control, the preamp is fine DC-wise.
To double check, measure AC V (lowest range on your DMM), it should be zero or close to zero.

Now connect the source to your preamp (no music playing), turn on the source and preamp. Measure DC mv at preamp output again. If the meter shows a reading, DC or AC, your source is defective.
To be certain, measure ACV (lowest range) and DC mV at the source's output.
If your meter shows a few mV DC or AC, your source is defective.
I hope this helps
I must admit, I've never seen a bigger collection of lost audio nerds than on this post. Leoturetsky, don't f*** around with exotic experiments. Eliminate one thing at a time. Do have your preamp checked for DC first, then if ok take out the zobel's and try your system. Then take out the Goertz if necessary. I'm sure the problem lies within this range of eliminations. Do you have a dealer nearby?
Hi Leoturetsky,
I wish I could give you something more helpful, but they're not just in airplanes anymore.
There is one thing I can tell you for sure . . . when problems defy repeated attempts at diagnosis, there is a fundamental assumption being made that is untrue. In this case, it's definately possible that there is/was more than one completely unrelated problem . . . that is, whatever's plaguing the Classe isn't necessarily the same thing that was afflicting the Adcom.

Noise that changes when cables are moved around is very common indicator of RF interference. Unshielded interconnects are especially suceptable, which is why I feel that they're basically worthless. But it's unlikely that it's another piece of audio gear putting out enough RF into the air, with sufficient field stregnth to cause a problem with anything other than radio reception. More likely it's some kind of nearby transmitting device, or something like a preamp output-stage going into oscillation and dumping RF directly into the amplifier.

DC usually manifests itself as noise that occurs when swiches and controls are being operated, much less common as steady-state noise. It also frequently triggers protection circuitry at unanticipated times.

In your system, I couldn't figure out what preamplifier/processor you've been using other than the Cary . . . problems that are volume-control dependent (with no sources connected) point pretty strongly to this component. And it's also hard to imagine that the Krell wasn't just defective in its own right . . . there's that thing about "it wouldn't turn on" that's usually a bad sign, and usually unrelated to other stuff.

Anyway, keep us posted on your progress . . . I just think that there has to be an element of coincidence and bad luck here.
Leoturetsky, did you try a different speaker cable? I doubt the cable is an issue (I've used them for years) but its best to eliminate as many variables as you can.
I plugged everything into the one PS Audio Quintet (not UO). Every 3-prong cord got a cheater plug except the preamp (Cary Cinema 11). I have not taken out the Goertz cable because I want to make as few changes as possible at one time.

Using shorting plugs on the RCAs of the Classe amp, 1.5mV AC, 0V DC, at the right speaker output of the amp.

For the next test, before I measured I noticed the volume control on the Cary was ridiculously staticy particularly as it increased the volume.

Using shorting plugs on RCA Input 7 of the Cary, and Micro Purls to the RCAs of the Classe amp, 0.45V AC fluctuating, 0.2V DC fluctuating, at the right speaker output of the amp.

Thats 0.2 volts, not millivolts. By fluctuating I mean it was never constant but those were the high numbers. When the preamp RCAs were disconnected from the amp, the number slowly dropped to zero and held steady.

1) Is this really the problem?
2) Why does the amp care about DC at the input and how does DC break it?
3) Shouldn't the Classe be shutting itself down if I turn it on while moving the volume control back and forth?

This is why I switched from ECE to CS....