I just noticed more than 2 years using Roon with a bi-wiring speaker set-up that volume leveling and headroom management (either/or) were killing my sound as if it was stuck in pressure cooker.
So to anyone in a similar case, just turn both off and enjoy unrestricted sound.
I use Cambridge audio 851W amp and B&W 704 speakers (the german made ones).
I cannot fathom how the use of bi-wiring which, essentially has no substantive effect on anything, can have an influence on the implementation of upstream DSP.
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I can just talk about my experience. When i first installed my 704’s in single wiring to my 851W amp it took me 3 minutes to say i will return them… the sound was a mess with a mix of bass and midrange twingled togetherwith very little separation… the 704’s are 2 and a half way speakers i have to say. So before packing them back i decided i would try bi-wiring as the bi-wiring was already there for my previous infinity speakers… the result was just magic with every low, mid and high falling in place and well separated. That’s all i can tell you and it might be specific to my set-up.
I’m somewhat perplexed - what does your bi-wiring experience have to do with volume levelling and headroom management in Roon?
Also, as @mitr pointed out, bi-wiring should make no audible difference whatsoever (despite popularly misheld beliefs). If it is making an audible difference, something is fundamentally wrong.
Are you saying bi-wiring made a difference, or turning off volume levelling and headroom management, or both?
Volume levelling shouldn’t make any difference to sound quality. Roon uses 32 bit 64 bit (corrected) in its volume control, so it’s audibly lossless.
Headroom management is part of the DSP functionality, so it would only be active if you are applying DSP. Again, headroom management is a reduction in overall volume to prevent DSP gains from exceeding 0 dBFS and causing clipping, so is audibly lossless. It sounds like you may have had some sort of DSP processing enabled, which may more rationally explain the sound quality issues you described.
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And the use of “volume leveling and headroom management” negated all that? Hard to understand how that is possible.
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64 my friend 
I m sure you’ve checked it, but just to make sure, before you’ve bi-wired your speakers, were the shorting strips in place?
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Oops, my bad, indeed it does. My old brain cells are confused. I was remembering 32 bit from a discussion with Kelly on the Benchmark DAC3 digital volume control! 
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“Also, as @mitr pointed out, bi-wiring should make no audible difference whatsoever (despite popularly misheld beliefs). If it is making an audible difference, something is fundamentally wrong.”
I can assure it did a big difference, in my case ar least, and i can understand it would not in other set-ups.
“ Are you saying bi-wiring made a difference, or turning off volume levelling and headroom management, or both? Volume levelling shouldn’t make any difference to sound quality”
Bi-wiring did make a difference to sound quality… turning off volume leveling and headroom management made a difference to the power delivered to the speakers which expanded their potential and delivered more details…
Sorry if this negates your technical geeky knowledge for which i am just an amateur, but one thing i am sure of is my ears… they’re sharp!
As @Boris_Molodyi asked, were your jumpers connected properly beforehand?
Before the bi-wiring of course they were.
OK. It’s pointless to ask you for evidence.
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True except if you come over 
. But If your system permits you can always try…
I could see bi-amping making some difference but b-wiring… It is electrically equivalent to having the jumper in place 
Unless jumpers weren’t making contact.
“…the false notion…that 'my ignorance is just as good as your knowledge.”
- Isaac Asimov
AJ
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Fine to sound less ignorant my understanding of bi-wiring is:
with bi-wiring One pair carries the high frequencies and the other will carry low frequencies from the amp. By having this set up, you are forcing the tweeter currents and the woofer currents to run in separate cables.
It just might be, as i said earlier that this is making a difference with my speakers and the crossover circuitry they carry.
That is not how it works. Both cables run full range because the passive crossover network still is inside the loudspeaker. There is no active or passive crossover upstream.
AJ
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Nope. For that you would need a (usually active) crossover before the power amps.
When bi-wiring, both cables carry the full frequencies because the crossover comes after them. What bi-wiring does do is that it changes the cable inductance and the capacitance that the power amp’s output stage “sees”. A few amps are sensitive to this electrical load (most aren’t) but then it would be easier to just use a speaker cable that isn’t wrong for the amp.
So what you are saying is that what cambridge Audio explain in the following link is just BullS… even though they also are for trusting the crossover built inside their speakers rather than bi-wiring…
It might just be that the CA 851W is one of those amps… can’t really tell… i just can tell what i hear.