Mixed amps for Active IBL's?

You won't be able to use a NAXO that way.  With the NAXO and SNAXO 2-4 one amp is dedicated to each speaker, so the amps need top be closely matched. The change came with the SNAXO 242 where each amp was dedicated to either HF or LF.  Here you could mix different Naim amps.

I believe it is quite simple to rewire the NAXO internally to dedicate amps to HF/LF. 

 You would need to check with Naim on what they will do with the NAXO.  It may not be worthwhile as the SNAXO 2-4 was quite a big step up on the NAXO performance-wise, and the SNAXO 242, even more so.

Unless you intend on doing it yourself (I would advise great caution here as it's easy to get it wrong and at best get poor sound and at worst damage amps and blow drive units) in which case that puts the conversation well outside of forum AUP.

I used to have a 250 and 160 driving active ibl's.  I never found it as easy to follow the music or relax to as either amp passive. It was always best with the 250 on high frequencies and the less good amp on the bass. I found two 250's to be very much better.

I ran mine with two 180’s for a while with a snaxo 2-4 and it was brilliant. I wouldn’  mix a 250 and 140 though even with a Snaxo 242. I wouldn’t mind betting that two 140’s, naxo/snaxo and hicap would sound pretty good. Not necessarily better than one good 250 though.

Thanks for the advice guys. Looks like I stick with the 250 run passive until another orphan CB 250 comes knocking  on my door.

 n.