I use OtsAV to play my music on my PC, via an Audiophile 2496 soundcard then into my amplifier.

I have recorded the audio going into my amp and it peaks in Adobe Audition at just below 0dB according to the meters. Is that too loud or should it be alright? I never hear any clipping caused by the amp, I just wanted to make sure I'm not damaging it in any way by inputting too high a volume.

Looks like you're fine. The lack of audible clipping on the output is a good sign.

I'm not sure how much you can refer to the level in Adobe given that the recording level gain on the A/D converters of your soundcard would prevent any signals from being over 0dB even if it were clipping. You should zoom in on the peaks and visually inspect to see if they are clipping to be sure. Even then you won't know for sure if the clipping was from the soundcard output or the input, but given they're coming from the same sound card you should be safe in assuming they are compatible.

It would be pretty rare for a soudcard output to damage the inputs to an amplifier - more likely that you would suffer from clipping long before that could happen. You do want to have the highest output level possible from the soundcard without clipping to make sure you're getting the lowest overall system noise floor.

You may want to check the maximum input voltage spec on your amplifier to see if its possible to overload the input given the sound card's output, just to be on the safe side.

Thanks for the advice DM, cheers :-)