Tube Rolling the Jolida/Black Ice dsd Dac


So I recently purchased the Jolida/Black Ice dsd dac and and a pair of Psvane 12ax7’s.  Played thru about 50 hours and while the soundstage opened up some, in my system detail seemed a little rounded off.  They probably need more hours, and  I recognize these are highly subjective impressions and system dependent, but then a friend gave me a pair of Fisher-era Telefunken’s to play with and I have tons of inner detail, imaging and a wide soundstage.  What I do find, however, is I have turn the volume up further on my passive pre-amp.  I have a pair of 50’s era RCA grey plates coming next week.  Pretty easy to go down the rabbit hole playing with tubes, but that’s half the fun of it.  Curious as to what other tubes Jolida dac owners are using. My system: NuForce STA-200 amp, Luminous Audio pre-amp with Walker mod, Bluesound Node2, and DIY LeCleach horn speakers. Mix of Cullen and Transparent Cables.
renisnceman
Also @jjss49 a gentleman above suggested Mullards.  But you suggest  philips ecg green labels - I am going into an ARC tube preamp - so I am thinking maybe too much tube on tube sound - any idea which tube would be the most analytical - not even sure if that is the correct term.

@plaw

i have not personally tried old stock mullard 12AX7’s but i have plenty of experience with old, real Mullard 12AU7 and 6DJ8 equivalents, for small signal tubes (not power tubes)

if the sound signature holds true to 12AX7’s you are asking about, yes, they are more rounded sounding, mid bass looser and fatter, highs rolled off... a very ’tube like’ tube, if you follow my drift

sometimes too much of a good thing, depending on the circuit they are used in, but very helpful when a user is trying to tone down harshness or stridency

philips ecgs are newer tubes (made in late 70’s and early 80’s) they are more transparent and extended, less midrange heavy
I’ve been pretty happy with the old stock Telefunkens.  After the SR Orange fuse, I added a Nordost Silver Shadow with bnc/rca adapter.  It replaced a Silnote cable and for the money it was a good purchase.  In my system, resolution went up another notch.  Still looking at those Mullards, though....
Regarding the fuse ,I mod the Jolida DSD wifi dacs I have modded several 
with a Substantial increase of fidelity on every level,the stock IEC is cheap tinned
brass , I put in a Furutech Gold Copper 3 x better conductivity much lower noise floor to start , the fuse you putin with theSR going in RS or facing << Thst is the correct way ,going towards the power side, then WBT copper connectors vs brass ,  then a choice of clarity Caps ,CSA or top of the line VH audio new ODam couplingcaps, not much room in there so a 400 v cap is the largest 250 v is sufficient 
from there you have tons more resolution , a good vintage tube will only make it better , NOS  50-60s Amperex are very balanced especially from the Herleen factory in Holland ,must’be tight matched ,Andy at vintage tube, or Brent Jesse audio , are the two best know out there . The psvane mk-2 tubes take at least 100 hours to settle in.
If youtruywant better detail send the dac back to Jolida 
fir sure don’t use the volume pot it robs detail period .Jarred said 
they can by pass the inexpensive static pot,
landforms $250  they will add 2 Vishsy naked resistors on the input ,and output and you can also upgrade to WBT rca connectors 
if you choose to ,butbypsssung the volume pot andthe 4 Vishsy naked resistors a worth wild upgrade, tubes maybe after That.