Vocal recordings result in lame volume

[Brightbelt]

I am on an iMac Pro (2017) using Catalina Osx. I just upgraded to Pro Tools 2019.12 but this problem existed before I upgraded to vs 12.

I use an Apollo UAD2 thunderbolt interface, and I use either an NPNG preAmp or a Great River preamp for my vocals.

My vocal takes seem fine when I record; the wave form looks healthy and everything seems ok. But when I play it back, I have to max out the fader to get any real playback volume.

At first I thought I had broken my microphone somehow. Then I tried different mics and it happened elsewhere too....

Note that this however, can be Intermittent. Sometimes the vocal take shines through. But it's unpredictable it seems.

I've tried changing mic chords, changing XLRs, using different preamps...

If anyone has a clue, I do appreciate any help or suggestions. The mics I use are an AEA R44CE and a Microtech GeFell GMBH. These are top notch mics and that's why this is kind of bewildering.

Thanks for any assistance, Frank