He could very well have had either a hardware or a software limiter/compressor in the chain and had it set totally wrong.
Forgot to mention that he had a small Mackie mixer in between the computer and the speakers...I presume to offer more inputs for playback since a lot of writers play from their phone output and iPad etc. It was a cheesy 4-channel board with no onboard effects so I know that wasn't a factor.
WHat do you mean it wasn't a factor...? It was very likely the MAIN reason.
The other point is ( and might be a moot point due to his mixer) ..... the fact that your song was triggering it so that the music was a mess.... I would have to wonder why. Are you using compression or some other things to kind of tame the peaks at all? Is the song itself a hot mess of peaks or is it relatively even? I understand the concept of dynamics and really try to keep my music vibrant in that respect, but by the same token, I seek consistency in the levels so that nothing is out of kilter in the music and on any given system, I'm not ripping subs out of their baskets or frying the high end tweeters. Ideally, you wouldn't want the music to trigger the limiter so drastically.
But of course, you could be doing everything absolutely right.... and it's just that the guy you saw was clueless on compressors and limiters and was doing what he thought he saw some studio engineer do or say in a recording/mixing session he happened to be attending. Just because he has an office and works with a major Nashville A&R firm doesn't mean he knows what he's doing in this respect.
It would be worth looking into to find out what went wrong because those A&R guys tend to go on what they hear and feel.... meaning, if the song doesn't sound good..... either poor recording or even if he has his playback system set wrong, your good song gets passed on.
In the future.... don't rely on the A&R guy's rig. Carry your own playback system that YOU KNOW and know for a fact sounds good. A simply MP3 player, with the song cued up, and a nice little portable but decent sounding playback amp/speaker combo.... something that fits in a small back pack.... or can be easily carried. No huge boom box needed...... That way, you know the song will sound good and can be presented in it's best light. Have a CD for the guy if he likes the song so he can listen again later..... but since first impressions count..... make sure it's a good one.
Note: at our songwriter meetings, I always bring my own player. More then one time I have seen the leader's player not work right.... songs don't play, don't sound good, skip, you name it, and me, as a listener, well... I'm listening to the distractions and not focusing on the song. The A&R guy will be doing the same. So be sure you bring your own player from this point on. Getting into the A&R guys office is a big thing so don't blow it with a crappy playback on his computer. Many will not give you a second chance.
good luck