Through out most of EMT-B school I used a super cheap sprauge. I think it was lie $12. I do not recommend using these unless for IN CLASS. Sure, they aren't terrible, but with the dualtubes... movement messes up what you are hearing.
I upgraded to an ADC Adscope.. I don't recall the model, 601 looks like the same according to a quick image search on google. I liked it. Heard fairly well, but the ear pieces got to be a bit painful after awhile. So , unless you change them you will probably be uncomfortable as well.
During medic school a friend gave me his old master cardiology and it was fantastic. Although, I think it was "too good". When on the ambulance you could actually hear the engine running and sometimes even the road noise.
I also got a cardiology III. I use this most of the time. Very comfortable and have great hearing.
For shits and giggles, I got one of those gold plated scopes so I could look like Dr. Romano from ER. No, it wasn't a real one.. those are actually $300+. Mine was a cheap ripoff. It was mostly for laughs.. but it worked.
So, with all of that said, I suggest something cheap and reliable. Go with the ADC and replace the earpieces.
good luck!