Input trim and VU meters
 

I was recently shooting a concert with my Rode NT3 and a Sony ECM-908C as a backup track. I had the ECM-908C on an FX7 set to auto, and the NT3 set to manual on a V1U.

When I was previewing the audio for the NT3 through headphones at first and everything seemed fine, but at the time I was on auto. I switched over to manual and made sure to turn down my levels quite a bit so my VU meters were only at half-way. I really wanted to avoid distortion and overloading, however now that I'm playing back the footage everything sounds MUCH worse than when I had the camera on auto. And my old Sony ECM-908C sounds way better than the NT3.

I'm presuming this has something to do with the input trim function -- I wasn't using it. Does the auto-mode compensate for input trimming or is it just making sure that the VU meters aren't peaking? Cause I figured it was just doing the latter and felt as though setting it to manual and monitoring it myself would've sufficed.

Also, are mic attenuators and limiters considered the same thing...and is that what I need to buy?

Can't speak specifically to the V1U as I'm not familiar with its metering and controls but as to your last question, no, a limiter and an attenuator are not the same thing. An attenuator uniformly reduces the signal level by a fixed amount across the board - with a 10dB pad in the line, for example, a signal at -5dB will be reduced to -15dB while one at -15dB will be reduced to -25dB. A limiter, OTOH, lets the full signal past unless the level exceeds a user-set threshold level where it is clamped off and not allowed to go higher.