"Electronics World" Magazine published these ‘hi-fi annuals' in the late 50s/early 60s;from what i can gather,they seem to be collections of reprints of the notable audio-content that EW published in the prior year. I picked up this 1960 edition a few years ago in the excellentAntiques Mall of Madison;some excellent vinyl LPs and rare paper dealers as well.
Anyhow. This mixer has some interesting features;nice simple circuit for calibration pot for DB meter;the best part though is the output stage: a 6AK6 tube is used into a 10k ohm load and promises a .8 watt output. I am not aware of any other hi-fi line output stages with 6AK6s;def want to try it. .8 watts output would very welcome in many of my builds… can't get enough of that clean headroom…
Here's the schematic (included in the download as well).