Rch, While a mono plug would work fine, A TRS (stereo) plug will do no harm. The ring contact on the jack is not connected. 73, Don W3FPR On 7/3/2020 8:58 PM, Rich wrote: > Is it OK to use a 1/8 stereo male on the LINE IN female jack? Fred's > book shows the RING is floating so I guess having a TRS male would not > matter. >