I drop kick test all my parcels prior to shipping. Like you say, you don't know what some whiny baby is going to do to your parcel. Best to let the guy that built it figure it out, since you have done all you can on your end.
I will share a little story with you. I bought a high end Phono preamp (1g) and it hummed like a mofo, I hooked it to my Yamaha, my Denon and my 35yr old pioneer and it still hummed like a mofo. 3 different systems entirely, I sent it back and they said it was perfect, dead quiet and it was reputable brand. I bought a different brand and it hums too, though not to the same degree mind you ,go figure. I wrote most of it off to old house wiring syndrome. Also there is so much damn electronic interference in a house these days , god knows what is doing it.I managed to reduce it down to a manageable amount using a few tricks here and there.
Keep us posted, always good to know how things work out.
