i had two aryas. One bought brand new from retail. and the other bought from a member from this forum. Both cans had the exact same issue. The left channel had lower volume than the right. As a result, the voice, which is typically recorded in the center of the sound stage was shifted a little to the right. The right channel basically sounded louder. It had more bass, treble, everything. This was a deal breaker for me. for a $1.5k headphone, this should never be acceptable. So I sold both.
TBH, this is very common with hifiman cans. I had the same issues with my THREE pairs of Sundaras. Except, with those, the left channel was louder instead of the right LOL. Honestly, ive had with Hifiman headphones. One of, if not the worst QC of any headphone company that ive dealt with. I was actually considering buying a HE1000se but the qc issues have put me off big time.
Do yourself a favor, if you face channel imbalnce issues with your Arya or any other Hifiman Headphones, contact customer service and get a refund. Chances are, if they send you a replacement, it might also have the same issue. hifiman doesnt seem to understand the importance of QC. Also, if you are considering buying a hifiman can from the buy/sale section here in Headfi, ask the seller about QC issues. I made the mistake and payed dearly for it.