Don Sach's pre amp

Also, do note that input impedance to Don (or any other manufacturer). If the preamp design uses output capacitors you'll need 8uf caps to prevent any low frequency rolloff (https://www.v-cap.com/coupling-capacitor-calculator.php).  That'll limit your boutique cap choices unless you've got no budgetary constraints. If you were to buy the miflex copper caps yourself, it'd be $500 at partsconnexion... And they're huge, maybe too big to fit. 

I'm sure Don will have some options for you however. The mundorfs are smaller and cheaper. 

Thanks, cal. Lots of variables. You’ve obviously put in a lot of work and money to find what works for you. I’ve been sticking to the easy changes, such as rolling tubes in the Lampi. I had a bad experience with the sale of my DSD, so I’ve got it back and am listening now with a PrimaLuna Dialogue preamp that came with old Mullards, while I await the return of my Lampi and think about whether or not to ditch the PL for something better. People -- developers and users -- were correct that although counterintuitive, sticking a good preamp between dac and active speakers, i.e., amp, improves the sound. Finding the right preamp for one’s tastes and budget is the trick.

@highstream Wish I could comment more about preamp options, but the DS pre is my first. Prior had run DAC direct from the PWD and DSD. Like you said, adding in a preamp is really a huge improvement. Counterintuitive as it may be. My reading did convince me that any relatively simple preamp circuit either based on 6SN7s or DHTs would be optimum. I suspect many of the simple 6SN7 pres (Supratek, the DS kit, deHavilland, etc.) would all be excellent and more similar than different.

Also, just checked my pre's height and it looks to be under 8" tall with tubes (and some vibration control).  A little hard to check inside the cabinet.

Has anyone tried Grant Fidelity's Treasure Globe 6SN7-SE?