I have had a look back through some of Joe's posts on the A-136
(#307), and can add a little more detail: in order to prevent *any*
hard clipping, the input signal needs to be less than about +/- 2V.
The level knobs 'L+' and 'L-' don't quite tie in with what is
suggested by the manual fig 1 p3: to get the highest (positive)
clipping level you need to set L+ at 0 (fully counter-clockwise), and
lowest (negative) clipping level is with L- at 10 (fully clockwise).
Thus as you increase L+ and decrease L-, more and more 'clipping'
takes place (according to how A+ and A- set!), as you progressively
'squeeze' the signal between the two
values of L+ and L-.

Tim

[The views expressed above are entirely those of the writer and do not
represent the views, policy or understanding of any other person or
official body.]