What separates should I use for my vandersteen 1c?

I know the Vandersteen 1c speakers are good but I am not sure why you want to spend $5000 on a $1200 pair of speakers? There are many great tube integrated amps out there that will blow your Onkyo receiver away for a lot less than $5000. Some of these tube amps are very easy to use.
Rogue Cronus $1800
Prima Luna Premium
Granite Audio
Jolida

5000.00 would be better spent to upgrade the 2ce signature II or a used pair of 2ce sigs at least. That is truly the sweet spot in the Vandersteen line. Everything better than it costs a LOT MORE but the speaker far above the 1 costs less than a grand more after discount.

I have the new Audio Research VSI60 with the 2ce signatures. I find it a perfect match, but it will run you around 3.5-4k, leaving you a grand to up to the 2s.

Get a good digital rig and you're set for life.

Wanna really set your ears on fire, get a good turntable
and add a great phono section...........lots of great new vinyl out there and it is truly the only real high res source.....ask richard vandersteen.....

Could the integrated Krell KAV 300i be a good match for Vandersteen 1C?

Buy a used pair of NC400 mono amps for around $1800 and the balanced preamp of your choice. I have been using a Jeff Rowland Capri with mine. It mates very well. The performance level you will experience comes within a short distance of the finest electronics available today for around $3000 total.

@Macrojack

I've read only great users reviews about the NC400. Seems like
it could be a good friend for many years to come. Thank you for the info.