Responses from hk_fan

Esoteric DV-50
I already have - nothing there unfortunately.  :( 
Need really simple advice. How do I use the DAC side of my ARC Ref CD-9SE to stream music?
Using a PC or Mac Mini is a great way to start.  I used my Mac Mini connected to my Ayre QB-9 DAC with a USB cable (I use Audioquest Diamond since you asked), and played Tidal and Amazon HD streaming services.  I recently replaced it with a Lumin ... 
spend on the streamer or on the DAC ?
They’re both really important.  I recently upgraded from a Mac Mini to a Lumin U1 Mini and the improvement was massive in my system.That said, I would start with the best DAC you can afford and plan to add a streamer as your next upgrade since you... 
Will streaming ever be "audiophile-worthy"?
I agree, it already is.  I used Tidal for a while and prefer Amazon HD but streaming is a fantastic source - in fact it's my only source! 
velodyne dd plus? still considered best of the best?
The DD subs use to be cutting edge, but like others I would not purchase one now with the new ownership and questionable support.One of the most musical subs I've heard is the Aerial Acoustics SW-12, however these are pricier than the others you m... 
Primaluna EVO 400 vs. stock Cary SLP-05 preamp?
I also vote for the SLP-05.  I owned the 05 as well as the 98 and the o5 was significantly better in my experience.  The fact that your modded 98 was better than a stock 05 is very impressive!  I'm curious to see how the upgraded 05 stacks up. 
Preamp or DAC?
@Kellen - Amen, you are not alone! 
Ayre KX-5/20 & VX-5/20 v AX-5 Twenty
I've heard both of the systems you are considering, but not at the same time and not with your Kef's so it's very difficult to provide meaningful feedback for you... however, I remember being impressed with the Ayre integrated.From my memory it of... 
AQ Diamond USB Cable with Ayre QB-9 DSD?
There is only one way to find out.  Music Direct has a 30 day return policy so you can try it out without risk.I recently added this cable between my Mac Mini and my QB-9 DSD and the improvements were incredible in my opinion. 
Ayre QB9 Dac . Upgrade to the new QB20. Vs competition In the $4-5k range or less
I have been told by someone that I trust that the Twenty version of the QB-9 is as good as the QX-5.. he owns both.  I am due to have mine upgraded in about 2 weeks and will report back. 
ARC LS 26 and Nagra
@big_greg is spot on.  The LS26 is anything but tubey sounding, which goes for just about anything with the 6H30 in it IMO. 
Pass Labs Power amps choices
The XA is where you REALLY want to be IMO. 
Whats on your turntable tonight?
DMB - Live at Continental Airlines Arena 
Most organic / real / analogue sounding DAC (ideally with Volume Control) for $1500??????
Another vote for the Ayre QB-9.  It still holds it's own against much pricier DACs. 
A speaker audio journey over: Classic Audio Loudspeakers T1.5 Reference = End game
I've heard these at RMAF driven by Atmasphere electronics and it was by far my favorite room.  Congratulations!  If i had the space and money I would likely recreate that system and live happily ever after.