Audio Tweak gone bad...similar experiences?

Was the penny oxygen-free? Sometimes the OF pennies, in a desperate attempt to obtain oxygen (especially the older ones), will steal oxygen from nearby components. (I've had tweeters, CDPs, even cables go like this.) I think you had such a penny, and your DAC was the victim. I'd do a diagnostic on the DAC, checking for blue ICs or a faint wheezing in the output stage.

I find dimes to work better because of the silver content vs the copper in pennies.

Don't forget to give this information to Classe's repair facility. They probably have a quick fix as this is a common cause of equipment dailures. Also, the techs could use a good laugh.

I feel that in the interest of the 'brotherhood of man' I must divulge,without concern for my self interest,i.e 'profit',that I have found the most 'awe'some tweak yet.I have cryoed some conch shells that have been laying around in the household for years,(picked up during dives in the Keys).You would be truly amazed at the effect these things have on the sound characteristics of audio gear.I figured that since one can 'hear the ocean' in them then certainly they should be a cinch for making a mid-fi system such as mine sound much more expensive.Since not everyone lives near the ocean as I do,I would be happy to cryo some and ship them out,for a small fee to cover expenses!

I've found that the drunken penny is really the best way to go. Find a canditate of the appropriate vintage, and break it in by bathing it in pure grain alcohol for AT LEAST 24 hours. (I've found that vodka can also work well, but you'll need to break it in for at least a week if you go that route.) This way, even if you're so unfortunate to pick one with some spiteful karma, it'll at least be appeased and/or confused enough to not be aggressive. Trick is, you'll have to repeat the process approximately monthly or the little bastards can get hung over and downright mean. You really, really don't want that. It also helps to have two or three in the bath, more or less all the time. That way you can rotate one out at a time and always have a couple of backups appropriately sauced. Also, they seem to perform better for not having to drink alone -- so having a couple of backups is not just convenient, but also the key to being a good host. Treat them right and you'll hear the difference.