The Octave RE320 is a 4 x KT150-based class A/B push-pull pentode amplifier of 5Hz-85kHz bandwidth, -110dB S/NR(!) and 130wpc/4Ω power (20% less into 8Ω). Switchable RCA and true balanced XLR inputs of the same output level accommodate various preamps. In signature Octave style, bias is adjustable to generate the most useful power. It's child's play to tweak via rotary trim pots and precision LED colour confirmation. As a thoroughly modern design, all heater and high-voltage rails are controlled by auto-monitoring logic for comprehensive fault detection, protection and from it, extended tube life. The latter is further promoted with a multi-stage 30sec. soft start and 2min. power-on delay timer. Without signal, eco or sleep mode kicks in after 10 minutes to reduce idle current from a 180-watt to a 20-watt draw. Full power consumption is 550 watts.

Three ECC82 of different origin play input/driver duties. A selector conveniently located on the back panel allows the use of KT120/150 (high power) and KT88/90/100, 6550 and EL34 (low 75wpc power). The through-hole PCB use 130μ thick copper traces for proper current conduction. The Black Box (x 4) and Super Black Box (x 10) increase the power supply's capacitance to support 2Ω current stability and minimize load impedance interactions with burlier speakers. Input sensitivity is 0.8/1.6V on RCA/XLR respectively. Input impedance is 220kΩ/ 20kΩ. Overall voltage gain is 28dB. An easily removed tube cage is included as is a screw driver for bias adjustments.

A look under the cover continues the modern leitmotif. Whilst flying leads are unavoidable, the core building block is a circuit board for 100% repeatability. For a small look behind the scenes, refer to our syndicated Octave factory tour here.

"Your HP700 loaner is a new unit because of a shortfall with other demo units. It is equipped with the control module and optional transformer-coupled line input module to accommodate your various balanced sources. The tube set installed is a valve of the E280/282F family, tube position D3. The regular EF184 (tube selector position EF) is also included so you can compare. The HP700 offers seven inputs, two of them modular. If there is no input module mounted to slot 1 or 2, the corresponding LED on the front won't light.

"If you switch between IN 1 and 2 then to IN 3, there will always be a short mute delay of the output. This is necessary to suppress switching noise in case a Phono MC input module mounts in slot 1 or 2. I think it best to start listening with a DAC connected to IN 3, power amp connected also via RCA, with the output selector of the control module in position 'all on' and gain set to the MED position."

When the call from Schenker came for directions to our digs, I was ready in more ways than one. Vivid Audio had just dispatched a Giya G4 loaner set to elevate my resident speaker game to the big times. I had three weeks before those were due back. That meant plenty of overlap with my Octave assignment. Not only could I test Andreas' RE320 amp on manlier speakers than we own, the South African 5-driver 4-way's resolution and distortion levels were superior too. This promised a hardware assocation on the level; plus an appropriate load for the amp and its add-on 72'000µF SBB option. That's important. After all, you wouldn't buy a Porsche Cayenne, then never take it beyond 3rd gear. In case you were hazy on the 'RE' in 320, it's short for Röhren Endstufe. That's German for valve power amp. By separate shipment, I also received a Metrum Adagio, a very sophisticated R2R converter with variable reference voltage for the possibly most purist and direct way to execute volume control. That'd serve as the HP700's transparency barometer.