Just a little update:
I was the 1st semester nursing student who thought his nursing career was over before it even started due to a jet airplane related hearing impairment he never knew he had until he tried to hear through conventional stethescopes.
The Littman 3000 & the Thinklabs ds32a were both recommended to me on this site (thanks to all who provided input). 3M let me try the 3000 for a week, & I did way better than how I had been doing, Think Labs sent me the similarly priced ds32a on a 30 day money back deal, & all I can say about that unit is, WOW!
Before I got some bugs worked out adjusting the ear pieces I thought I liked it, I got the ear piece issues worked out & I played with it yesterday, & compared it to a Cadillac; after spending more time with it today, it's not a Caddy--it's a Ferrari!
This is coming from someone who has now ascertained his hearing is pretty wrecked, but I can hear bowel sounds clearly while I'm checking heart sounds! I've got it turned up all the way (Think Labs claims that to be a gain of 50X), & my wife says that is wayyyyy too loud for her, but all I can say is I can hear clearly & that does a whole lot towards making me feel better.
The impression that the Think Labs excellent customer service gives me (& I won't go too esoteric as I'm trying to convert my thought process from that of a mechanic to that of a nurse) is that this unit is hard wired from the bell/diaphragm to the earpieces, so it is an analog/digital hybrid from start to finish. If it is turned off, one hears nothing, & in that case it is dead as a piece of wood, but there is a switch (when turned on) to completely defeat the gain, & in that application Think Labs tells me one is listening to the equvalent of an unamplified conventional steth.
(The Littman 3000 has a gain of up to 18x. The impression 3M gave me was that all the amplification happens at the bell/diaphragm piece, & from there up to the earpieces it is conventional. I heard better than with my conventional Littman (a Master Classic II), but there was a lot of noise that I wasn't always sure were body sounds or background because I wasn't skillfull enough with it. Had I not tried the Think Labs, I'm reasonably sure I would have bought the Littman.)
I am green as a X-mas tree to this stuff, but I can also say that I don't need to be a Cadillac expert to know when I am riding in one. Okay then, thanks to all who provided input to my 1st thread, if I don't make it in this game, it won't be because I can't hear.