Hello. My system with the 990 as the processor was calibrated so 0dB on the volume display was my reference level, and that produced a +14dBu nominal level on the XLR output as measured on the device connected after the 990, which have precise metering. If we accept that +22dBu is the cliping point of most equipment using XLR connections, pro or consummer, that would leave 8dB of actual, clean analog headroom over the maximum level found on digital medias (0dBfs), with the 990 volume knob being able to go up another 6dB higher that that, namely +14 dB on the volume display.

Now for the 976, being a drop-in replacement in my system, I found that having -10dB on the volume indicator is giving me a similar but not quite as loud actual SPL in the room (not measured but I estimate 2dB SPL). Since I'd rather have an easy to remember number as reference, I choose to stay at -10dB, which is also sitting well with me becoming older and more sensible to too loud hahaha!

However, if I'd use +2dB volume position as my reference, the 976 would have the same 8dB of clean analog headroom (same headroom as the 990) but not *more* gain available above that, since volume max out at the 0dB position.

Now, the Outlaw support said that the channels level calibration (done in the digital domain in the setting menu) has another +6dB of gain available. If one was to use it, the net output level should then become the same as the 990.

For short, the two processors have different gain structure and "volume" scale but should ultimately be able to give the same output and gain (ie Drive).