Sound quality: Sony's SRS-XV800 had lower range overall sound quality - this model has sonic shortcomings that leave a lot to be desired when listening to music but don't rule it out for dialog. With the tone controls of the Sony Music Center app set for the most even tonal balance, the bass has good impact and goes fairly deep but is somewhat prominent and boomy. The dynamic range can sound a bit compressed with some program material with impulsive content. Midrange is even but is somewhat hazy and grainy, a bit muffled and echoey, and a touch plasticky. Treble is extended but is somewhat subdued and smeared and a bit sizzly. Does a decent job of recovering the actual room ambience from the recording but the echoey quality of the midrange adds an artificial sense of room ambience, and the overall sound is somewhat congested. When two units are used as a stereo pair the sound stage can be made wider depending on placement. There is no significant difference between Bluetooth, optical, USB, aux inputs. It can play very loudly, but sounds strained at higher volumes; without sounding strained can provide a decent volume level in a large sized room.