Tony, the QS receivers overseas have a DB in the model (e.g., STR-DB780 and 'DB1080). Sony used to use the DB designation in the US as well. The STR-DB830, 'DB930, 'DB840, 'DB940, and 'DB1070 were all available in the US as well as other parts of the world. For some reason, Sony never put the QS badge on the US components. This was true for the Sony MDS-JB920, 'JB930, and 'JB940 minidisc players that were all marketed in the US. For some reason, Sony just this year discontinued the DB designation in the US and now has the US equivalent models as part of its ES line. I believe the 'DA1ES and 'DA2ES in the US are eqivalent or at least very similar to the 'DB780 and 'DB1080 overseas. We get a break in the US since the ES models come with a five-year warranty.
Well, I have a DB830 that has performed extremely well over the years. When we get our new theatre room built I will probably move up to an ES receiver with external amps. I have been happy with Sony receivers over the long haul, still have an old one that we use in the study, it is about 10 yrs old. (Although it was a base "consumer" model, so I guess it is crap. ) Never had a problem with Sony receivers.
TimG