Advice on a preamp

YW Shamus. The Pass INT-250 is $12kUS. I crunched some numbers & reckon if you sold your current amps & used up your max budget you would be close. I think the Pass will give you all the qualities you’re looking for & would be a killer amp. The Vitus would have a more refined/transparent top end, but the INT-250 would have a bit more power/control.

Thanks for that Melbguy. I will have a chat with the NZ importer today and see if he can arrange a home demo via one of his dealers (they only carry amps and pre's here in shaky Wellington, no integrated. I appreciate your, and everyone elses input.

I have an Aesthetix Calypso Signature with the Sanders Magtech running Magnepan 3.7i's.  It sounds pretty good.  I was upgrading from an Odyssey Candela.  It definitely yielded some gains.

I liked the Aesthetix Calypso very much. It is easy to roll different tubes as well.

Happy Listening!

" Great question. A cleaner more detailed sound, better bass control, more refined treble and improved soundstage. An all around more 'live' or natural sound. I did originally have an Opera 100w tube amp but felt it was lacking in power and a bit too warm."

That's some good info. I would demo an Ayre K-5 for SS, and for tubes I'll be the 3rd to recommend the Calipso. You can't go wrong with either. 

Your amps are fine.  Unless you're not happy with them for some reason, I would keep them.