You are to be commended for caring that your audience got the best possible performance. At least you did get a good story out of it. Since none of it was your fault, I hope you went to church yesterday for a little celestial chat about this. Is there a patron saint for soundcrew or techies in general yet? If so, they need to be informed. (I attend a Methodist church, but it doesn't stop me from having a word with certain particular saints, as needed.) On the secular level, most of the audience, whether they know you or not, will remember the feedback and the sound crew's botch-ups, or they were chasing after their children or somesuch dealing with small problems, not paying the rapt attention they would in a hall. A lot was going on that day, and your part was a small portion of it for them. If you'd lost your temper onstage or something, they might have vivid memories of the afternoon (a bad thing), but as it is, I think they'll just remember that they had a day out, including music.