You will have a shift in listening experience if you move from Ascend's with RAAL tweaters to a more traditional cone and dome type speaker like Vandersteen. The soundstage and listening experience is just going to be different. Not bad, just different.
If you like a ribbon tweeter and want a warmer presentation, I would look at Scansonic. Something like the MB5-B or MB6-B would work in your room. I have a customer who is driving this with a PrimaLuna integrated using EL34s in a big room so it would be fine with your Pass.
Another option that could be really interesting is the Audiovector R3. I know this is a bit above your budget but it is a great speaker. Andrew Quint had a great review of it in TAS a while back.
I carry Scansonic. I have no affiliation with Audiovector. I just think it is a good speaker.
