So the Avantalk is now with "normal Bluetooth" absolutely great!
Update 09/19/2013: I have bought a second Avantalk because I'm now just absolutely loved the part, already without apt-x! I have my Bose QuietComfort 15 connected to it, at a Sony Xperia Z that goes from really! The maximum volume is also quite high. The Avantalk seems to have built a good amplifier! I really give full credit, because I'm just thrilled!
Update 6/24/2014: The devices with apt-x take thankfully finally something! I have now a Sony Xperia Z1 Compact and a Sony Xperia Tablet Z2 can test the Avantalk, and I am absolutely thrilled by the sound! Why apt-x is mostly still do not or rarely mentioned in these reviews smartphones, pointing to a large ignorance of editors towards :-( Since these times should finally inform you!
Frank M.