Bit the Bullet ... Don Sachs Model 2 Preamp

Also, the output impedance is about 410 ohms.  That number is irrelevant.  The only thing that matters is the size of the output capacitor in relation to the input impedance of the following amplifier.  .47 uF will drive about 80K or higher and be flat to 20 Hz.  For 47K amps you need 1 uF output caps and for 30K amps you need 1.5 uF.  Base prices of my preamps include a wonderful Polish oil cap in .47 uF.  Going to 1 uF costs $80 and 1.5 uF costs $120.   Anything larger than 1.5 uF requires that I use a Mundorf silver oil cap because the Polish caps are the same size as Duelunds, and 1.5 uF is the largest value that will fit in the case.   

Anyone know what the gain of the Kootenay 120 Amp is?...
I’m trying to mate 10” stereo subwoofers with a selectable gain Hypex Amp.

I’m happy to share my experience - Happy Model 2 Preamp and Kootenay 120 Amp owner here for 1.5 years. I’ve previously used non-corporate builders like Odyssey in the past. There’s always some trepidation at first, but Don’s excellent communication, customization, and attention to quality has made it a worthwhile and pleasurable endeavor that continues to yield excellent sonic results.

I’ve found the Golden Voice KT88 to have reliable filaments compared to the Black Treasure KT88. It’s sometimes luck of the draw with Chinese sources, but Don is a respectable guy, and guided me in the right direction. I wouldn’t go anywhere else for sourcing these tubes. The Black Treasure KT88 and Golden Voice KT88 sound equally engaging, detailed, and extended. The Golden Voice is a little brighter at first, but after 50-100 hrs, it breaks in and settles in beautifully. The beauty of Don’s Amp is that the KT88 auto-bias, so they don’t have to be matched quads.

In the Preamp, adding the Psvane CV-181T was like a veil had been lifted - open, transparent, extended, detailed, 3D, and airy, without losing coherence. It’s the best 6SN7 variant I’ve used so far. After trying the CV181T, I relocated the Shuguang CV-181z in the buffer position. I’ve tried NOS Sylvania 6SN7GTB Chromed Tops, RCA 6SN7GT, and sounded a slightly darker. I found the Psvane CV-181TII to convey more detail, openness, soundstage, without any edginess. The coupling caps are Jupiter Cu for tube output, and Mundorf Supremes for solid state output. I also have another set of outputs for subs and XLR.

My phono preamp is a Manley Chinook with a matched quad of NOS Telefunken E88CC. It sounds great on the Don Sachs system... I’ve made DIY interconnects using Duelund DCA 20ga oil-impregnated wire, replacing the Shunyata Venom IC. I’m also using the DCA 12ga for speaker wire. The Duelund yields more micro-detail, coherence, and `````````````````````````````````````````````````````````````````````````
My only wish is a future integrated tube amp... :)

Yes Don Sach’s stuff is amazing. I have the preamp. Totally silent and lots of dynamics and great detail. Also had his amp for a little while too. That had lots of resolution. Had recently installed two dedicated 10ga audio lines and it was pretty sweet. I returned it because it was also damaged during shipping. Have him triple box the shipments. Paying the extra for another box is completely warranted. 

In case anyone out there is looking for one of these on the used market, I just put my heavily upgraded unit up. I've loved it for a year and a half, but recently commissioned a two-chassis all out assault built around the EML-20AM.  It retails for almost twice the cost.  

I think my DS2 is likely the best sounding one in existence.  Pure silver signal wiring, duelund CAST capacitors, silver WBTs, copper shielding, etc.  A lovely pre that took my system to new heights. 

For people who already own the pre, I do strongly recommend the capacitor upgrade if possible.  The pre gained a great deal of refinement and 3-dimensionality when I added the Duelunds.  I also really liked Mundorf SGO Supremes in that spot.  Amazing imaging, but a very slight reduction in bass for me.  I found the stock Miflex's to be a bit 2 dimensional.