Best significant upgrade? Dac? Preamp?


Hi guys!

Im hoping some of you with knowledge of my system can help me make a good decision about my next upgrade.
I would like a surprising and obvious difference not hard to spot subtle change.
From my research i think the next move should be the Dac.
I would like to explore DSD,i have some SACDs now.
my system:
Mark Levinson 320s preamp
(Would i see a difference with a ML no.52?) I am also looking at the no.52 ,would i see a big difference compared to the 320s? Worth the extra $$ ?
interconnects: Acoustic Research master series silver high definition RG6
ML 431 amp
XLR: +bo ? +ba ? Only info on them

Wilson Audio Watt Puppy 5.1 speakers (serie 7 tweeters) +transparent music wave plus cables
Arcam rdac (wifi) with Teddy Pardo power supply.
Running on mac air (usb) ,Tidal HIFI
(i currently listen most of the time to this vs rarely SACD).
Thanks!



128x128nicsaudio
Get a tube amplifier. Something like a VAC 300.1 or VAC Phi 200. Or perhaps one of the big boys from VTL or BAT.
I know PS Audio ,nice design and i heard good reviews,will look into that!

I must have looked at DACs for at least 10 hours and its getting confusing as to what i should buy.  :-/
Its a risky investment due to high purchase price and quick depreciation because of technologie advances.

Should get a TUBE to warm up my sound a bit?

Budget around $1000-$1500 looking for a deal worth more since i tend to be able to keep a few years and sale at purchase price without losing.

I have a Monster 3600 MK II power filter.
How important is it to pay more? 
I always thought my power filter was doing a good enough job.



Concerning DACs inhave seen good reviews on Lampi and Chord but they are really expensive !
I'm Cleary biased since I now sell PS audio gear, but the new torreys operating system that is in beta right now takes the DS dac to another new even higher level.  The direct stream Jr is lower cost and uses the same OS.    
I also agree power conditioning makes a huge difference.    I'll make a post about the new one from audioquest I just got in.