Would it be a smart upgrade to go from a Sony STR-DA7es 44 lb beast of a AV receiver to a newer Onkyo TX-RZ840 just for the HDMI switching and the newer codecs like DTS-MA and DD TrueHd? I have been auditioning the newer Onkyo in my home for a few days and have a couple more days before i can take it back..I have been told that the amp section in the Sony DA7ES is far superior to the newer Onkyo but the Onkyo seems to be more authoritive especially in the bass, Sony receivers have always been know to be a little thin in the low end even their top models, i think the addition of a DBX subharmonic synthesizer might help this.Question would you upgrade the Sony STR-DA7ES to the newer Onkyo?
In that case may be you have a defective unit or something wrong with your settings. If not, then there must be something else at play causing it, but definitely not because it is a Sony. I have had two ES Sony receivers, the last one being the 4ES and never had that issue, would imagine the 7ES is much better than the 4ES in every ways.
Audioholics.com reviewed one of them, don't remember which one but I think it was the 5ES, and never reported the thin bass issue. Sony, like others, designed their audio gear to be transparent, from all available specs and measurements they have been solid, at least in terms of frequency response. Other reports of similar issues to yours, if any, were internet hearsay, that's all I can say.