Don and I are pleased that Raven owners have an equal choice between RCA-input power amps and XLR-input power amps. The Raven treats both the same, so the sonic choice is on an equal footing.
Classic vacuum tube amps almost always have RCA inputs, with phase splitting handled internally. Similarly, low-powered SET amps have RCA inputs because they are single-ended throughout, from input to output.
Older transistor amps from the Sixties through the Nineties typically have RCA inputs, with phase splitting done in a differential first stage with either bipolar transistors or FETs. Contemporary transistor amps may offer both RCA and XLR inputs, but the highest performance option is typically the XLR input.
It’s all the same to the Raven preamp, since all signals pass through the output transformers, which have both RCA and XLR output taps, just like the 4, 8, and 16 ohm taps on a tube power amplifier.
P.S. I should mention in passing the Raven may be used as a signal conditioner, like other "tube interfaces" on the market. It removes both DC offsets and RFI interference from other components and environmental RFI. Transistor amps often have issues with RFI incursion, which might not be as obvious as hearing AM stations in the background, but as an increase in veiling and listening fatigue. What’s actually happening are the input transistors rectifying incoming signals in the MHz (AM, SW, FM) to GHz (WiFi, mobile phones, Bluetooth) range, which then splatters IM distortion across the audio band.
Get rid of the RFI interference, and the amp sounds cleaner and fatigue goes way down. That’s where the studio-quality input transformer of the Raven comes in; it is designed to reject RFI, and preamp tubes themselves are resistant to RFI. The result is that all that comes out of the Raven is clean audio, in the 15 Hz to 60 kHz frequency range, with nothing above or below that. The audio-only feed to the power amplifier reduces the burden on the input transistors (or opamps) of the transistor power amplifier.
