FTD : Elvis Presley Soundboard Concerts on CD
Soundboard Recorded Concerts
A soundboard recording is the tape recording from the concert mixing desk.
Most of Elvis' concerts were recorded this way. The tapes were often used to give new band members an idea of previous shows. The concert was recorded at the mixing desk onto cassette tape, usually in mono. While they are in mono and were never intended for release, this is irrelevant to a large degree if the recording is good. And also if Elvis' performance is good.
There are also several professional RCA recorded concerts in the stereo section.