Thinking back, I recall that the Volume of 100 in MP1 was designed to drive the audio at its recorded (sampled) volume; the range was 1-127 in line with MIDI note velocities. I think that setting it to 100, allowing for some volume increase, rather than 127 was something I suggested, many years ago.
In MP2 there is a more intuitive Volume slider. Again it defaults to 0, meaning at the recorded (sampled) volume level, and allows some volume increase.
My thoughts:
Sending a MIDI note with a velocity of 100 (and the Vol set to 100 or 0dB) will cause the audio in either plug-in to play back at the recorded level. Sending a higher velocity note or turning up the Vol will make it louder.
I did some trials in MP1:
-- with three notes at different velocities,
-- and at two different Vol levels in MP1.
The resulting waveform is in the centre and the dark grey graph shows the true-peak levels. The green and red are the momentary and short-term loudness levels. Looking at the peaks, Note velocity of 100 and Vol of 127 is louder than Note velocity of 127 and Vol of 100.
Turn them up if you wish. But check out the sound if any effects are used, in the plug-in or after it. Some effects have a sweet spot - performing best for input within a particular volume range.
Trust your ears. Or get a second opinion.
