Recommendations for 5k upgrade


As winter approaches more time is spent listening so I have allocated this budget for system changes and/or improvement. Planned changes are marked between brackets.

Source:
PC based music server / SB Touch (ext. power supply upgrade, maybe Bolder?) fed into Eastern Electric MiniMax DAC with Dexa opamps. Alternative source: Sony DVP 9000ES CD/SACD via optical.

Amplification:
Conrad Johnson CT-5 with 6H30DR tubes, CJ LP140 mono blocks (tube rolling planned, which 6922?)

Speaker/sub:
Dunlavy SC-IV modded, Velodyne DD-12 or REL R305 (haven't decided which one to keep)

Power Conditioning:
Audience AdeptResponse 12 with e PowerChord (AU24e PC planned, dedicated 20A lines planned with the next room renovation)

Cabling:
IC: NordOst Valkyrja throughout (maybe Valhalla, looking for alternatives with better price/performance), NordOst Silver Shadow for S/PDIF
SC: NordOst Heimdall (probably the weakest link here, upgrade to Tyr2 ? Alternatives?)
PC: NordOst Vishnu to preamp and power amps, stock PCs on other devices (waiting for the final direction for PCs, not sure to stick to the loom theory, having all PCs of the same brand)

Isolation: mostly Black Diamond Racing cones/pucks and one BDR shelf under the preamp, some Stillpoints (planning to experiment with alternatives like Aurio, Symposium, etc, under the devices, maybe some for under the speakers)

Room treatment: just acoustic panels behind the speakers, need high WAF suggestions for my 21' x 30' room which has a half sloping cathedral ceiling and an open staircase. (looking for bass traps that can blend in with the interior for the corners)

I am not unhappy with the current setup but like to have more details without being too lean/bright.

What is my weakest link?

Of course YMMV but appreciate any suggestion to take this system to the next level without a second mortgage (or divorce) and/or improve the synergy between components. TIA!
polyglot
Update:

Following your comments and great advice I have upgraded

1.) Transport: to a Cary 306, more detailed, very sweet sound, I am having problem with the upsampler (which may be defective, have emailed Cary). A big step up indeed, thanks to all but esp. Zd542 for speaking very clear words.

2.) All power cables to Audience power Chord, conforming to the loom theory and based on my great experience with the Audience AdeptResponse 12T (this is just my experience as I don't want to again to start a war of words on cabling): blacker background, on the CDP and preamp I feel that the NordOst is faster and sounded better on violins in some recordings, need more time to hear the differences.

3.) all ICs from NordOst Valkyrja to Valhalla (my biggest expenditure) and not what I hoped for which is a minor upgrade so that I can sell those expensive cables: it was the biggest improvement of all: much more details, so fast, so dynamic! Very tempted to test a Valhalla power cord but all budget is gone.

4.) Fuses (thanks Vhiner for mentioning about it here) to HiFi Tuning and in the near future AMR gold so none of the devices will have standard fuse(s)anymore: this is the best bang for the buck, very recommended for all to experiment! (Again, I do not intend to start a discussion on this topic, it is just my personal experience that I wish to share).

5.) Isolation from Stillpoints and Black Diamond Racing under the source components to Symposium Jr Rollerblocks with Tungsten balls: worthwhile improvement, more solid sound staging.

Up next:
- now very much needed upgrade of the digital cable so suggestions are more than welcome here.

- will do some tube rolling and some tube proponents suggest, it is about getting a variant on the sound without buying another component and as Douglas noted, rolling opamps do the same.

As you may have noticed, I have stalled, for now, the DAC upgrade mostly due to budget constraints but more so because it has held very well against others in the past. One, less likely, alternative route is buy the new PS Audio PWD MKII and downgrade the ICs from Valhalla back to Valkyrja to stay in the extended budget but I am afraid that the overall result would be worse than the current setup.
Polyglot,

Wow! You've been busy and it sounds like you've made excellent choices. I also subscribe to the loom theory. Too bad you can't afford Nordost's flagship digital cable. I use Shunyata's Zitron Python digital and suspect the Lessloss may be similar based upon reports from others. If it is, it's an outstanding cable.
Vhiner,
I will, as mentioned, I am looking for used digitial cables up to $800. In fact, I have a Valhalla digital loaner, see which one comes close to it. Which other digital cable did you compare before settling on the Zitron Python? In my HT I have Shunyata power cords but am not, certainly after the recent splurge, contemplating about completing the all cables Shunyata loom there.

Back to the main 2 channel setup, just replaced the Heimdall speaker cable with Audience AU24e: less grain, better presentation, more harmonic depth. Will wait till I have settled on the power cords before deciding which SC is to stay, too many variables now but the system is trending towards Audience, taking ground from NordOst. It all started after the arrival of the AudienceResponse.