VinceJ is correct here. I have the OPN1 and was originally fitted by my audi with 85dB receivers. They caused distortion on the high end on my right ear (as you can see my loss from 2KHz and up is 90dB or worse on the right ear) and I had to have the gain dialed down by 4 to 6 dBs in the 4KHz and 6KHz respectively to get rid of the distortion.
I later upgraded to 105dB receivers and the distortion was gone and I didn’t need to make adjustment to correct any distortion. I had to pay $175 extra for each new 105dB receiver with custom dome ($350 total). Once you go up to 100 and 105dB receivers, custom domes are required. I would recommend 105dB instead of 100dB receivers simply because they cost the same and the extra 5dB headroom may help in the future if your hearing gets worse.
Audiometrix_hearing said that the 100 sounds so different, but my personal opinion is that the 85dB and 105dB I have sound pretty much exactly the same, little to no difference at all to me. As for more powerful receivers have more THD (total harmonic distortion), on paper that may be right but in my personal experience, I don’t notice any difference at all between the THD of the 85dB and 105dB receivers at all either.
I think the 85dB would fit you OK and if you experience any distortion like me, the gain can be adjusted down a little bit at the right frequencies to fix that. The 85dB receivers are much less conspicuous than a custom mold for the 100+dB receivers which sticks out a bit more with a big tail/horn that’s totally visible on your ear.
I asked my audi whether I could have been fitted with 105dB receivers up front for the same price instead of the 85dB receivers, and she said no, the original cost only covers up to 85dB receivers with a standard dome. If I go to custom mold and/or a larger than 85dB receivers, I would have to pay more for the larger receivers plus custom molds as extra ($350 extra for the pair/set) anyway. But if you have insurance that would pay for any of the extra cost, I would recommend you go with the bigger receivers up front so this cost is picked up by the insurance. I had 95% insurance coverage and made the mistake of not upgrading to the bigger receivers later so I had to pay the $350 completely out of pocket later on when I could have had my insurance company pay for 95% of it up front. But that’s OK, it’s not that much and I now have a pair of 85dB receivers as back up to use in case I want to have my HAs looking less conspicuous or in case I have to send in my 105dB receivers in for repair or wait for replacement.