r/AposAudio

The SI-1 sits between your network switch or router and a network audio component, providing active optical-electrical isolation across the Ethernet connection.

It uses independent optical transmit and receive channels, dual femtosecond clocks, and a linear power supply with a dual-winding potted toroidal transformer. The isolated output supports Gigabit Ethernet, while the electrical separation also helps address ground-loop and network-borne interference issues.

It’s a fairly specialized piece of network hardware, but the design is aimed squarely at systems where electrical isolation is worth pursuing.

Check the details of the Matrix Audio SI-1 at Apos.

I had a great time showing off my latest work in the bay area this weekend! Hificon is an awesome event set up by the local community, and i couldn’t miss the chance to catch up with some old friends and try all kinds of gear in a much more intimate setting than the usual Canjam.

Pictured are my own Sierra and Laguna headphones, the latter of which is a prototype still in the works.

The FiiO IMP XLR-4 is designed to run compatible headphones from a home HiFi power amplifier. An internal voltage divider attenuates the amplifier’s output and helps reduce background noise before the signal reaches the headphones.

It supports 16–300Ω headphones and compatible amplifiers below 300W. Outputs include both 4.4 mm and 4-pin XLR balanced connections, with 4 mm banana jack inputs for the amplifier.

Check out the FiiO IMP XLR-4 at Apos.

FiiO has moved into full-size tube amplification with the EA13, a pure Class-A push-pull design using two SYLVANIA NOS PCF80 preamp tubes and four JJ ELECTRONIC EL34 power tubes.

Speaker output is rated at up to 28W + 28W into 4Ω or 8Ω, with at least 18W + 18W at THD+N below 1%. The amp uses custom EI output transformers and separate speaker terminals for both impedances.

Connectivity is straightforward — four RCA inputs, a 6.35mm headphone output, and a 12V trigger input. There’s also a 40-step analog volume control and mechanical VU meters, because apparently a tube amp still needs something to look at while it warms up.

The EA13 comes in black or silver.

More details and specs here.

The Magni Piety is back in a limited Brass Knob edition.

Originally based on an experimental Schiit prototype, the Piety takes a different path from most modern solid-state headphone amps. Rather than chasing the lowest possible THD, its fully discrete Continuity-based design was intentionally tuned with distortion characteristics and gain behavior that are closer to tube amplifiers.

A few highlights:

• Fully discrete, massively paralleled transistor output stage
• New variation of the Continuity circuit
• Limited edition solid brass volume knob
• Two-step gain switch (1.8x / 6.3x)
• Up to 1W into 32Ω
• Output impedance below 0.6Ω
• Hand-assembled in California

If you've been curious about the Piety but missed earlier runs, this version is now available at Apos.