Biases are subconscious orientation, tastes,past decisions etc, influencing our perception and evaluation.
They may be positive biases, as a musician asking and waiting for a specific sound in his practice, or negative biases (placebo/nocebo) as an audio fool waiting for a necessary increase in quality because a new purchase...
But negative or positive they may be acquired by a long practice history in musicians case, or by sound engineers and acousticians working for decades in their field...Positive biases are expertise...
I did not wait to buy a new upgrade to reach a better sound quality...
Happily for budget reason i could not, then i resolved to create my own tweaks and for 2 years, 7 day /7 i experimented with many acoustics concepts in my dedicated room.
(resonators and ASW/LV ratio, absorbing/diffusion/reflective balance, locations of resonators not only their mechanical tuning, non conventional tweaks as Schumann generators grid, ionisation , minerals grounding of the gear pieces, vibrations/resonance controls, speakers and headphones modifications etc )
I learned how to acquire new biases created by mastering acoustics concepts.. Which is way better than organizing a complex double blind test so interesting and instructive it could be for sure as it was for the OP and i dont doubt him on this as a very informative process in itself....
In audio they are two groups:
The subjectivist hate blind test.... The objectivist like them...
The two groups are driven by a common gear obsession...One hate blind test because he judge the gear by his hearing biases the other group only look at measuring dial to evaluate the gear, his biases as conflating perceived sounds qualias with Fourier analysis...
But it is the same blindness to the necessary and useful positive acquisition of new biases under experiments driven by acoustic concepts...
One group for example promote cheap low cost dac as good and the costlier one as snake oil in need of blind test...
The other group swore by his costlier piece of gear as the best for his "taste"....
I grounded my dac (low cost) and put it in acoustical optimal environment.... I used an objective set of conditions regulated by my subjective trained hearing....It was enough for me...
I cannot pass a double blind test because the sound qualities i am used to perceive and evaluate pertain to this specifically designed room of mine, with the piece of gear i specifically modified with tweaks and others means...It is a unique environment if we make the sum total of all acoustics factors which exist in only one place : mine...
I do not claim to perceive absolute good sound "per se" everywhere in any condition, i claimed to be able to improve only mine with basic concepts...
Double Blind test are industrial tools to test or debunk claims...
They are of no use when you test different resonators for example many times each day for 2 years as an acoustic hobby...
i learned to trust my ears in these specific conditions...I used simple blind tests hundred of times for 2 years by design and choice tuning resonators or by chance (forgetting to put the Schumann generators button "on" for example )
I do not have bat ears no more than a piano tuner had...
But i know what is best in my specific room without need of double blind test which will be impossible to do in my room anyway...
Thanks to the OP for this interesting audio society location and article...
There is even a section dedicated to tweaks...
A great interesting site...