Pre amplifiers build by me

Preamplifier with Tube 26 Pure DAC DSD and r2r volume controller

Preamplifier picture1 Preamplifier picture2

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This preamplifier use an R2R volume controller by danzup followed by a 26 Tube triode amplifier with transformer output.
Dac is Amanero usb module configured as pure DSD DAC.
You can search diyaudio for Amanero DSD DAC.
For R2R atmel controller you can find the complete documentation on internet