Possible sulphur issues in an apple brandy

[NormandieStill]

Back story: Last year was not a great apple year around here, but we did manage to press 160 litres of apple juice into a wooden cider barrel to make calva. After a little experimenting the year before I had found that the ferment using the natural yeast on the apples, produced the most flavourful (albeit lowest yield) low wines. So this year we decided to run the whole batch on natural yeast. Fairly early into the ferment I could smell some sulphur, so (as I had the previous year), I fed the yeast some nutrients, and while the smell didn't go away, it stopped getting worse. The previous year I had dumped a copper tube into the bucket which seemed to clear up the smell, but this year it had already faded when I came to distill so I didn't think about it. My still is stainless, but I have a bunch of copper pieces in the boiler, a roll of copper mesh in the vapour path and a copper condenser, and I've not noticed any problems in the past.

The problem: While I was running the spirit run, I would take a few drops on my hand and rub them together. The residual smell when the alcohol had evaporated was not very pleasant, a little like the smell on your skin the day after you've been chopping onions or garlic. I wondered if it was just the alcohol bringing out a smell that was already on my skin.

I've now tried three times to blend my jars, and that damn smell is everywhere. It finally more or less peters out about 4 jars from the end (the last two jars came off very cloudy so I called it quits). The cuts are proving to be a nightmare. I can smell and taste differences between the jars, but the smell (and a harsh burn that I associate with it now) covers everything so I've no way of knowing what's going on.

As of yet, I've not touched the backset, so while it is depressing, the option remains to just dump everything back into the boiler and start again, but if this is a sulphur problem I don't see how a rerun will make anything different. I did see a reference in an old thread to using hydrogen peroxide on the low wines to clean up some more persistent sulphur compounds. Has anyone tried this?

Has anyone had a similar problem in the past? Will it age out if I can crib together a blend from abv and trying to find the flavours under the onion? This is the biggest run I've done yet, and I've got about 12 litres of distillate from which I was expecting to pull somewhere between 4 and 6 litres of hearts (based on prior efforts). Given the work involved, I don't really want to bin this if there's some way of salvaging it.

HELP!