I just use iodophor and tap water. I thought for a bit that tap water might be the issue, because I think we have chloramine here - but all the other brewers in town seem to have no problem with it, plus the real evidence is that I've also done 3 or 4 partial grain recipes (Wayne's broggot-docio, a maple ale based on the previous grain bill, a weird darker low ABV ale, and a low ABV light coloured spruce tip ale) that used extract plus specialty grains, then had either whole hops, hop pellets or spruce tips. These beers had exactly zero of the taste/aroma I'm having a problem with.
None of those had this very distinct flavour. The heavy and bitter I made almost hide it behind bitterness, but it's still pretty clearly there, the cheapo "lager" had it in spades, it was pretty much the main taste, and the red-ale I'm not totally sure about yet (still in secondary) but it smells like it'll have the taste too.
For the heavy and bitter I used the kits exactly as advertised (they come with 2 cans of hopped LME so need no extra sugar) and the other 2 kits I added either LME or DME instead of adding dextrose.
Very sorry for hijacking this thread!