Did you purchase all these headphones at full retail (not subsidized by manufacturers)? If yes did you sell any? If yes which one?
How long have you had all these cans at the same time and how much time did you spend with each?
Did any of the brands (including brands of any electronics/cables/other accessories) sponsor the video or sponsor any other videos or any other marketing efforts?
Are you in discussion with any of the brands (including brands of any electronics/cables/other accessories) re sampling or future product reviews?
Did any of the brands review or comment on the video before it was published?
Do you have affiliate links or will you be otherwise compensated for products purchased through any link or offer codes you provide?
What’s your qualification to provide such comparison (other than having the cans to test)?
These are questions I've answered in the reviews of the individual pieces, but didn't collect in the video.
I bought, modded, and assembled the TH900 Lawton I used over several months. I have put a lot of work into it and am not going to sell it.
None of the other headphones in this comparison came directly to me from a manufacturer or retailer. They were loaned to me by independent third parties;
@sa11297 being the main lender and
@damadaka loaned me the Arya se.
None of the brands have pre-viewed or commented on my reviews before posting. I would not agree to such an arrangement.
After my Arya se video posted to YouTube, I was asked by HiFiMan if I would like to do reviews for them. They have provided review samples for the Edition XS (also posted) and the HE400se (review pending). They have made no attempt to influence my opinion in any way.
Apos Audio, which provided no gear for this review, has sent me review units as well, mostly Topping amps and DACs. I post affiliate links for those products in the descriptions of my review videos and make sure to disclose that they are affiliate links. I mention this here to point out that even though I have financial incentive to say positive things about Topping gear, as well as the pressure to maintain relationship with the provider of review samples, I don't hesitate to point out the shortcomings of the gear sent. Please watch my Topping reviews if you don't believe that.
So far I have made no profit from my review work. I run it mostly at my own expense out of my basement simply because I enjoy listening to and learning about this gear and sharing what I learn.
As far as qualifications...I have an intro video on my channel where I talk about where my love for music and gear comes from. Professionally, I'm a physics professor. That's my "real job". I enjoy it and it is what supports me and my family. This review stuff is fun on the side for now.
Reviewing on YT is a relatively new endeavor for me and I hope it continues to grow.
I hope that answers your questions.