Thiel 3.7's and Pass Labs xa60.5's- now looking for the next upgrade

I finally took the plunge and bought a pair xa60.5's mono's to drive my Thiels- and the upgrade has brought my system to a whole new level.  I was looking to get a deeper, more developed soundstage and with the Pass mono's I got more than I was expecting: the speakers virtually disappear, and you can see into the performance- the sound has a much more refined texture and everything is more fleshed out.   So now I am wondering what should be the next step up.  What I am looking to do is to get more spatial cues, and I suppose detail, to have a better sense of the recording venue and bring me closer to that sense of a live performance. 
My intention is to stay with Pass Labs and the Thiel's so I am thinking more of a preamp or dac upgrade.  The preamp is a Primaluna Dialogue Premium with Telefunken Nos tubes and the dac is a Moon 280d.   Cabling is Nordost except for the power cords to the amps which I built myself and which really did make a very marked difference- more bass and presence than before with stock cords.
Both the dac and preamp are very good in their own right so changing either to get a significant upgrade along the lines I described above rather than a sideways step isn't going to be easy.   So I am interested in any advice and thoughts from fellow audiogoners.

Here is a brief description of how my system evolved.  I was originally driving the Thiels with Mac MA7000 integrated- the power amp section is basically a hot-rodded ma252.  The first upgrade I decided to try was to bypass the preamp section with the Prima Luna and that was a revelation. The sound was transformed.   Then I started doing research on a replacement for the Mac altogether.  It took me a long time and I considered a lot of options.  What put me on the path to the Pass Labs was the suggestion from a friend, an electrical engineer that is also passionate about audio, that I take a look at a Luxman class A amp.  I had never really considered this option as the Thiels are not easy to drive but as my friend pointed out the issue would not be the watts as the Thiels are 90db but the power supply which needs to feed an impedance load that does dip below 3 Ohms across a significant portion of the frequency spectrum.   Anyway, I wasn't able to find a Luxman at my budget and it was than I got the suggestion to consider Pass- the xa30.8.  I was intrigued and called Pass and had a long conversation with them and they indeed are very familiar with the Thiels- and they too confirmed that their amps would have no problem driving them.   Anyway, just as I was mullling this over a pair of xa60.5's came up at a good price from a great a'goner and so I went ahead with that.  And btw, I have heard some suggest that Pass does not deal well with low impedance loads- it is simply not the case- not at all in fact and the proof is in the pudding: the Thiels sound GREAT.

Anyway, any suggestions and advice would be great.

Many thx as always!