Break in of Link DAC III

I purchased a link DAC III with half nelson upgrade a couple of weeks ago. I'm not overly impressed with it so far. While it is an improvement on my Rotel RCD 971, it's not night and day like I had heard in the audio store. I understand that break-in is required, but just how long are we talking here? So far, i have about 50 hours on it. Will there be a significant improvement in overall sound?

Associated equipment:
Rotel rcd971
Nakamichi AV10 top of line surround receiver (I suspect this is part of the problem)
NHT 2.5i speakers
KimberKable DV90 (i think that's it - silver coax cable)
audioquest type 4 speaker cable.

I'm starting to think that I got scammed into paying for a half Nelson upgrade that was never done. In other words, i'm worried that I just have the base model WITHOUT the upgrade, but that I paid for the upgrade (i'm not that trusting of the dealer - he seems like a scammer).

Main questions that need answering are:

1. Is break-in a significant improvement in sound quality? and if so, then how long does it take (and will it be a 'sudden improvement' or just gradual)?

2. How can I check to see if I ACTUALLY got the half Nelson upgrade?

any help for my worried mind would be appreciated...

Steve