I know exactly what are you talking about Riznich.
I'm not really into vocal recording and singing anymore but when I was devoted Judas Priest/ Rob Halford fun (back then in the 90's) I used to practice alot and every tape recording of our rehearsal sounded right but when I first tried to record my performance with SB Live Platinum and Beta 58 mic I could not believe how different and how thin my voice sounded.
I was embarassed to show our digital recordings to friends and blame it all on bad equipment, but even after I upgraded my rig to RME Hammerfall,condenser MK-319 and
TB 202 tube pres it didn't changed much. My voice had character, warmth and strenght on all of our tape recordings but on those digital it sounded unnatural and sterile. I needed to put so much effort when recording digitaly to sound barely acceptable. What troubled me is that my bandmates did not notice big difference but to me it was huge.
I am aware that my mic and pres were in budget category but still think that they should have sounded better than a bloody $100 2-track Sony tape recorder, dynamic Shure mic and Yamaha EMX mixer pres.
However, I decided to invest in some better vintage mic and pres and to try again, though it is not easy to make a decison im my homeland beacuse you can't just go to a 20 different stores and experiment with mic/pre combos to find best match with your voice, but perhaps that's just what you should do. It would be great to rent good mobile rig for such a purpose.