Aura preamp. "Over the STP-SE [right – Ed.], the PCB layout is revised and the circuit redesigned with self-balancing signal converters and complementary discrete Fet buffers with low loop feedback. Headroom for high drive has doubled and the XLR/RCA outputs (2/ea.) are driven independently so there's no signal conversion between the balanced i/o (there are 3:2 RCA:XLR inputs for a total of 5 in and 4 out).

"It's still a direct-coupled signal path without caps or opamps. The display has grown for easier legibility and new touch controls offer click-free adjustments. Improved grounding between my digital control section and analog signal path has further reduced interference and the discrete fully balanced resistor-ladder volume is now optimized to remove pops and ticks during level changes.

"The power supply uses dual-mono R-core trafos for zero internal or external hum and our firmware can now be upgraded by USB. The chassis is all non-magnetic aluminium and there is also a full-aluminium remote wand."

A point of distinction for EJ's preamp has always been its activated passive behavior below 63 on the dial. 'Activated' means input/output buffers for constant impedance. 'Passive' means zero voltage gain. After all, today's high-gain sources drive virtually all amplifiers to full output without any extra gain. The STP only kicks in voltage gain for extreme scenarios from 64-80 on the ladder control which in Stage II guise runs premium denuded Vishay resistors for the most-used range. This passive/active twist maintains a lower noise floor by eliminating unnecessary boost then bigger cut of the source signal. Gain is reserved for only when you really need it.

… to be continued…