If you are going to transmit music from your iPhone, you should be aware that it doesn’t do aptX, only AAC or SBC, and there’s no way of checking which codec it uses. In the case of Tento, the expensive version has AAC and aptX, the cheaper version I believe only has SBC.
I haven’t done listening tests on SBC vs AAC vs aptX, only checked on my MacBook Pro (which DOES do aptX, and where it’s possible to check the codec used) that AAC/aptX works on my Tento unit.
My inittial unit came from the first batch which did’nt have AAC/aptX, but sounded great anyway (through SBC), and so did the MyST siebling a friend of mine had (also SBC only, at the time). However, I wanted the possibility to use AAC/aptX, so had mine swapped to the new AAC/aptX version, when it became available.
If you have ALL your music on your iPhone, I guess you must be storing it in ALAC or AAC. It’s my understanding that when transmitting AAC (if both transmitter and receiver support the codec) you avoid transcoding, and theoretically this should mean better sound quality. This is why I wanted the AAC/aptX verison, as I would be using iPhone as source, like you’re planning to.
For various reasons I then ended up using PortaDAC in a transportable setup, rather than with iPhone, so never really got to make use of the AAC/aptX feature. As I said, SBC sound great also, MyST/Tento clearly found a way to extract the most of this codec.
All this to say, that probably the AAC/aptX verson is best suited for you, but the regular version sound fine/great as well.