Thanks Spleen for your kind reply!
Despite not having heard either the Audiosource S3D60 or the Zvox 220/420, I took a dive yesterday & won a Zvox 420 on EBay. I really liked what I read about the S3D60 on Amazon, however, the soundbar is a few inches too long for my TV stand and would not blend in well with the setting. I ended up going for the 420 as I did not want to sacrifice aesthetic harmony for volume, lol! I would have got a 220 if it were not for use in the living room, after all, the model has received quite a few positive reviews online from various owners. As a 220 owner, your testimony truly cleared my doubt about the sound quality of Zvox soundbars. Again, thanks!