At least I got an AR and it works very fine with the A4 
I also own a TI (Keys), really like its unique sound - but: TI is a desaster. So I considerd to throw my TI out of the window 
I think the A4 has its very own character of sound. For sure you can ‘imitate’ this on the TI, but A4 remains A4.
My advice: keep the A4 in your rig and get the AR!