DAR-reader Philippe G wrote to me with some thoughts on op-amp rolling in the Eastern Electric Minimax DAC. A combination of his enthusiasm and the Australian angle of Burson means Philippe’s words (and photos) might be of some interest to other readers:
“An informal guess: (Eastern Electric’s) Alex Yeung knows that the Minimax’s potential can be expanded by optimising the op-amps, that’s why the Minimax isn’t shipped with the op amps soldered to its board but rather there are sockets which allow for easy ‘op amp rolling’. The socket configuration of the Minimax means you can roll these almost a easily as tubes.
The Minimax is sold as a mid-budget DAC but with expansion options left open to take further advantage of the ESS9018 platform. One can’t blame Alex for not including this kind of op amps into the stock version given it’s lower mid-market price tag, but at least he left the door open for you to do just that.
I only use the two first of the Minimax four op amps as I pass through the tube gain stage only the first two op amps (U1 and U2 on the circuit board) are used by the tube gain stage.
I definitely think that this is the kind of op amp the Minimax Dac deserves, Bursons HD op amp seems to work beautifully with the ESS9018, it adds tons of detail, as well as a fair amount of airiness. All in all music gains ‘gestalt’, a more haptic, tangible experience altogether, very holographic. The timbre of instrumentation is also more natural and credible.
Extensions are enhanced : better, tighter and more detailed bass. Those highs gain airiness and outright extension, cymbals decay nicely and do so with additional detail to boot.
Prior to the upgrade there was some digital dryness and harshness to the sound of the Minimax, the DAC presented detail well (due to the sheer resolving power of the ESS9018) but an absence of ‘moistness’ troubled me. With the Burson HD op amp, this is now all gone. I now hear a sound that’s lusher and more liquid.
For the bucks spent, this is a crazy good upgrade.
The only downside being that due to the Burson op amp’s size it’s quite difficult to fit them in in a way which would allow to close the top lid, but as long as you don’t mind a little DIY aesthetic, it’s fine.
My setup is very basic but quite transparent: John Kenny modified HiFace (battery operated), EE Minimax DAC with Burson’s HD op amps and PSValve tube, as well as Virtue Audio’s Two.2 (also battery-powered). Mains power is filtered and RF shielded by Supra Cable’s affordable LoRad Shield mains block.”