Fiio FA1 and FH1s Comparison

[DiggyGun 43]

I’m looking to get my first pair of IEMs. After a good deal of viewing, searching and reviewing the comments on here, I’m drawn towards the Fiio models. 

Initially, I liked the description and look of the FA1 model. Now I’ve seen the FH1s which also has good write ups.

For a newbie in this area, I’m trying to understand what the differences are and what would be the best one to start with:
- The FA1 has a single balanced armature (one driver) and MMCX connections @ 15ohms
- The FH1s has two drivers and 0.78mm Double Pin connections @ 26ohms and Hi-Res Certified

Is there a big difference having two drivers over one driver
What is considered to be the better connector
Why have they changed from MMCX to Double Pin
What is Hi-Res certified
They will be used on an iPhone and at home on a headphone amp 

Many thanks in advance and looking forward to the responses

 

[DiggyGun 43]

Ended up getting the FH1s in the end and I must admit that I’m very pleased with them, the build quality and accompanying accessories are excellent. Also got a pair of the FD1 as a comparison. 
 

Been using both on the iPhone and through a Tube headphone amplifier and so far, I’ve been pleased with the results, once I got the external DAC sorted out.