Iain Purdon wrote:For those who may be wondering, what difference would we hear between original mono, and genuine (not artificial) stereo played in mono?
That depends on what you mean by "played in mono".
There are three systems which could be so described:
(a) something such as a 1960s mono record player of the Dansette / Fidelity / Bush type (mono cartridge, single lead from there to a mono amp and one speaker);
(b) a stereo system with a mono/stereo switch set to "mono" (meaning that the twin channels from the stereo pickup are combined at the input stage and fed to the stereo amplifier sections as mono; and
(c) a stereo system with no mono/stereo switch or with one set to "stereo", meaning that the twin channels are kept separate at the input stage and fed to the stereo amplifier sections (and thence the speakers) as discrete signals.
Leaving aside the issues of hardware quality, (a) and (b) should sound the same as regards the mix, though instruments located prominently in the centre of a stereo soundstage will tend to be more prominent in the combined mono "mix" whether on (a) or (b).
You'd think that playing a mono source on a stereo system would still produce mono (c) and that it would be the same as playing it on a true mono system. But with a vinyl source (or a source derived from vinyl and not processed further), a stereo pickup will often produce left and right channels that sound subtly different from each other in equalisation and compression levels. I get this all the time when transcribing vinyl to digital via a stereo pickup and routing. You can usually SEE a difference in the wave pattern on the computer screen. The effect is better (and more "monophonic") if the channels are combined before the pre-amp input stage - but... not many amplifiers have a mono/stereo switch these days.