Yeah, Mrk, if it's a friend of a friend that gives you credibility already. It's proof that you aren't some total creep. That pretty much goes for everything though, not just the FM system.
And yeah, Derek, you're right too--I certainly don't say to not be yourself. I wouldn't suggest he hide or deny hearing loss. Just that in the 2.4 seconds you have to make that first impression, passing a microphone might not be it. After a moment or two of flirting if there is a vibe there, THEN say, "Y'know I'm HOH and it's really hard for me to hear in this noise. Can you use this microphone that transmits to my HAs?" Some girls might just say, "Uh, nevermind" and walk away. But I'd guess most girls would be receptive. They just may need a moment to process it, and if they've already decided you're a potential date (trust me, we make that initial decision really quickly) they will make that effort. Girls are not expecting an FM system, so they should be given some benefit of the doubt in hesitating or being taken aback.
It's like if you took a girl to your turbocharged car, and all she knows is that they use more gas. Maybe she's really environmentally conscious. So you just tell her you have a super awesome car although don't tell her right away it's turbocharged. Then she goes for a ride with you and sees how awesome it is, she will totally fall in love with it and only want turbocharged cars after that. But if you told her in the first instant it was a turbocharged car, she would have walked away and never know what she's missing.