Itching to upgrade preamp...

You owe it to yourself to try Nelson Pass' B1 passive preamp.

@georgehifi I used to go direct from the DS Sr to the XA60.5, but inserting the preamp added quite a bit more space and drive. I do think the preamp is necessary to get the most out of it. Not that the DS is bad, just that the X0.2 is better.

Going through the P12 does actually improve the XA60.5. Yes, it looses a bit of low end slam, but it gains in terms of imaging. It's trade off that I can live with.

@oldears Maybe you're right... it could very well be that the X0.2 is not the limiting factor. Only way to find out is to demo some other pre's (trying a PrimaLuna EVO400 today). As to the room, not much can be done with the layout. It's a dedicated room, but I can't "turn it 90deg" as it would be too short. There's a mixture between acoustic panels and acoustic diffusers. I used to own a recording studio, so I'm quite familiar with acoustics to how to get the most out of the room (wouldn't call myself an expert, but knowledgeable enough not to screw it up too badly).

@d2grils I'm not sure a passive preamp would achieve anything... that would be just like driving the amps directly via the DirectStream Sr... does sound good, but you do lose drive and space.

@audiojan you may want to consider a Lamm Industries LL2.1 Deluxe preamplifier.  New Audio Frontiers Amati is also worth checking out if a remote is important.

Cheers,
Colin

Lamm Industries dealer
https://gestalt.audio

I would look seriously at the PS Audio BHK pre BUT you have to get different tubes.  The stock PSVanes were horrible.  I had NOS Tunsgrams that were amazing.  

It is balanced, will come in on budget with the trade or below budget if you buy used even with the NOS tubes.  
I upgraded from the BHK but my system is entirely single ended now.  I was using VTL Monos and had the DSD with Bridge II.  
I run all Art Audio gear (I am the importer) and moved to Chord for my digital.  My Conductor is 100% a better preamp in a single ended system than the BHK but in yours which is balanced, the BHK will be pretty great. Another perk is that it uses the same remote as the DSD. 
Two other options, the McIntosh C22.  Brilliant pre and it just is begging to have a turntable added to it.  The phono stage is obscenely good.

The ARC LS27/28...whichever you can fit in your budget.  Darn good preamp for the money and would work supremely well in your system.  
I have run the DSD direct into power amps previously and found it to be a significant step down in quality from a separate pre.