Next upgrade

The 72 was never designed to be used with a flatcap. So the first thing I'd do is get a Hicap for it. I'd then try a passive 250 against the active 90s. If you still prefer the latter, swap the IXO for a snaxo and Hicap. After that, turn to the power amps. 

That does suprise me, in the Nac 72 manual I have it clearly says you can. Anyway going active seems  give me better timing and focus. Vocals and acoustic guitars sound much improved as does the low end bass.

cheers Mike.

What I meant was that when the 72 was designed, the Hicap was its partner. The flatcap came later. It can of course be used, but it's not ideal. 

So what do you think, a pair of 140s or Hicap next?

I said what I'd do above. Hicap for 72. 

Cheers.

 I 

Agree. Go HiCap - Olive ones are not much money, pre-loved - but get it serviced if not done recently (within 8 to 10 years) or if unsure.

Cheers. That's the plan

I'd agree that a Hicap would be a good next move, but - if you're buying old kit like that, your choices will largely be dictated by availability of good used units, so if a suitable power amp comes along at the right price, I would be tempted to grab it while you can. 

I ran IBLs with an IXO and two NAP180s for a while. That worked well. My IXO wasn't great though and had a tendancy to put a loud hum through the speakers even when not in use. A SNAXO/Hicap will be far better

But agree with HH. Put a Hicap on the 75 first. Maybe keep the FC and use that on a SNAXO if you can in the future, pending upgrading that to a Hicap of course . The 90's aren't that bad so that would be my last change.