Oops, hadn't checked this thread in a while, sorry.
Jerry, as pointed out previously the R75 is equipped with a mute jack on the back. The Viking II and NC-300 are doing well, not seeing a LOT of action here in Summer but I did throw it on 40 early mornings, and on 20/15/10 during the days sometimes if I'm awake.
As far as the R75 mods, I simply sent mine to KIWA for some audio upgrades and the sync detector fix.
http://www.kiwa.com/R75.htmlIf one isn't afraid of surface mount stuff then check out Phil's page..
http://home.comcast.net/~phils_radio_designs/Phil_R75_Fidelity_Mod.pdfhttp://home.comcast.net/~phils_radio_designs/Phil_R75_Cookbook.pdfSo anyway, I take the audio from the record jack in the back into my soundcard line input on the desktop computer since it has a nice hi-fi 2.1 stereo sound system. AMers sound great with up to 15 Khz filter selections. I have an AM BC station about 4 miles from me that plays oldies and the fidelity is phenomenal on the R75 for a small power station (90 watts at night)