I got IB2 powered so far by a number of amps, latest being 7B SST.
I would not put too much emphasis on what a review or someone on forum says, it is highly subjective, system and room dependant, you have to hear it for yourself (I know, it will be nearly imposible).
Having said that, there are no speakers in their price range I would rather have.
And if we are discussing speakers regardless of the cost, there is only one other manufacturer that I may be willing to consider but only after an opportunity to have them compared to IB2 for extended period of time in my system.
IB2 works with Bryston exceptionally well for me. Just for the sake of comparison, I had Pass Labs X350.5 in my system and I preferred Bryston by a large margin.
If this sounds biased and comes too strong in favour of Bryston/PMC, I will mention that I did not like Bryston prior to getting IB2, do search on this forum and you will find me saying that “Bryston was not my cup of a tea”.
Now I cannot think of a better matching amp among those I heard.
So if you asked me, I would say to buy IB2 without hesitation, power it up with 4B SST or higher model (higher preferably but not necessary).