Vintage tube suggestions

Gennerlex is good tube but they have a smaller and flater soundstage. Also little drier mid and leaner bass compare to Tele or mullard tubes. And new tubes just Don't or can't produce that big 3D sound vintage tubes make. Vintage tubes just have more meat on every note. I can't tell if there is any difference in sound between smooth or ribbed Platte. Is your mullard reissued ones?

Yes rotaryphone they are reissues.

I am not sure how vintage tubes will work in your pre or DAC but I never had a where vintage tubes didn't improved quality of my systems sound. I can't really turn and go back to using reissued tubes. In my tube gears...Vintage rule.. lol.

I owned a Jolida preamp and using NOS was a vast improvement. If you are using Mullards in the Dac then maybe you should use a more neutral tube in the preamp.

Telefunken is very neutral, dynamic and has a huge soundstage. RCA BlackPlates are very open and realistic sounding, more like classic tube sonics. And inexpensive.

An important point is to purchase NOS tubes from a reliable dealer. Using Ebay is risky since the tubes may not be of the highest quality.