Joncourage,
My ears have recently been tested. I can actually hear above 16000 Hz which astounded me since I am in my 60s -- and I plum the depths, as well. So, I trust my ears. I always protected my ears when I was younger when attending concerts. I have worn wax ear plugs, when needed, for the past 35 years. I note that many of my audiophile friends who did not protect their hearing are now suffering from serious hearing loss -- some of whom I would affectionately call "handicapped" audiophiles.
Give it a go. You have nothing to lose by trying your cables in series. You may be pleasantly surprised. I recommend reversing them if the sound is not good initially. I find that doing so can often make a night-and-day difference.
My name is not Robert, by the way. Please see Robert's and my earlier statements regarding identity matters. If you are familiar with my posts over the years, I believe I could be accused of shilling for EMM, Merlin, Synergistic Research, ASI Liveline, HiDiamond, Gabriel Gold, Joseph Audio, Oyaide, AMR and Bybee, among others.