Having brewed various beers with SO4 from 0 ppm to >300 ppm my conclussion is that it mainly effects bitterness. The bitterness will be rounded with 0 ppm, and sharp with a lingering dryness at high SO4 levels. Hop flavor and aroma don't seem to change. You do start to get some sulfur aroma at high levels of SO4. That Burton snatch as they say.
I voted bitterness only. Although it can be argued that bitterness itself is flavor. But not the hop flavor I assume NiceFly was referring to.
See, you raise the point that got me thinking about this in the first place. How hops are described, or "hoppiness" Leaving aroma out of it for a minute, there is hop flavor and hop bitterness that often get described in the catchall term hoppiness. Then we get into the brewing aspect and sulfate increases "hoppiness". This is the sole reason I started looking into my water chemistry is that I moved and my hoppy beers lacked hop flavor. So I get the new water report, find out my water is softer than Pilsen, and say "ah ha that is why I am not getting hop flavor." Or in retrospect was it? So I adjust my water, bla bla bla, IPAs get back on track. Or was it because I found better ingredients? Then I get thinking about this Amber ale I am going to brew for the first time since I looked into water chemistry. I would like a bit of hop flavor in there, but I want it the malt to be the star. Do I use my malty water adjustment or my hoppy water adjustment? Does the hoppy water adjustment even matter for hop flavor? So if you are still reading after that ramble, I was just wondering if anyone knew whether the sulfate levels effected hop bitterness or flavor or aroma or a combination.
You could adjust calcium ,chloride and sulfate levels of your water, if you see they are too low as you stated above. I would start things up balancing chloride and sulfate in the 80s ppm while getting more than 50 ppm and less than 120 ppm calcium.If you would like to feel more hopping flavor you could try to add more late hops.Several hop additions in the last 20 mins of boiling.
