I believe this has already been discussed in another form, however, today I would like to maybe bring it up as this might be something a new person that has not seen the other threads might be confused about.
(The fuzz is always disabled by the way, not turned on when describing these symptoms)*
I had a great chain on both paths a and b. Yesterday I decided to add a fuzz, Arbitrator fuzz, to mess with. I was using headphones, it wasn't obvious to me the sound had changed. I went to go play at church where I normally play, still didn't notice because I play really loud anyways to begin with.
I went home to practice. I noticed how low my volume was on my practice amp, didn't think much of it. Then I thought about making a new signal chain to come up with new ideas. The moment I went to a new blank preset, all the clarity and volume came back. My amp sounded great again, good strong volume, very nice clean and clear signal.
I began testing things between my old preset and new blank preset. I found out that, if I delete the fuzz, arbitrator fuzz, on my old preset, the volume comes back with all the shimmer and greatness on the amp. So then what I did was, on the new blank preset, I added that fuzz. The sound went dull and low. So then I remembered that old thread and I started messing with the guitar input block. With the fuzz still there, if I changed the setting on the input block from "low z" to a much higher "ohm" setting, basically the further to the right the slider went, the better the sound came back, up until 230 ohm, I have a strat, and at 1m ohm the sounded became to crisp and brittle.
So based on that other thread I read, if you add a fuzz, you need to tweak this impedance setting on the input block if you don't want the sound going flat and dull.