<HTML><BODY style="word-wrap: break-word; -khtml-nbsp-mode: space; -khtml-line-break: after-white-space; ">Don't know if this helps, but I had the same problem with my Digimatrix. Turned out to be the audio input from the CDROM. Disabling (muting) it in Alsamixer fixed it.<DIV><BR><DIV><DIV>On Jul 5, 2006, at 9:24 PM, Owen Mehegan wrote:</DIV><BR class="Apple-interchange-newline"><BLOCKQUOTE type="cite">I have a new Myth system that I've just built. I'm using an MSI PM8M-V motherboard, with its on-board audio (Via VT8233/A/8235/8237 AC97) for everything. The system is connected to a Sony 34" CRT TV using DVI/HDMI cable. Audio is routed as follows:<DIV><BR class="khtml-block-placeholder"></DIV><DIV>cable box -> myth box -> tv -> Sony home theater receiver/speakers</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>All of that is done via basic RCA cables. My problem is that I have an intermittent 60hz hum in the audio. I hear it whether I'm watching TV or just in the Myth interface. Playing with various mixer volumes doesn't make it go away, in the sense that I can't null it out without having the whole system's volume down too low to hear anything. I have everything plugged into one power strip/wall outlet, and the outlet has three prongs; whether it's really properly grounded or not is anyone's guess. I tried unplugging various unrelated components (Xbox, cable box, cable modem/router) and got no change.</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>So, any suggestions on what I should do to clean up this audio? Maybe buy a better sound card? (And use spdif out while I'm at it? My receiver can handle it, though it's a pain in the ass from a "management of the available inputs" perspective.) What if I bought a UPS and plugged everything into that? I've seen suggestions of "home theater" magical grounding thingys... if you think one of those would help, a link to a specific product would be sweet. Thanks!</DIV><DIV><BR><DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><FONT face="Helvetica" size="3" style="font: 12.0px Helvetica">--</FONT></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><FONT face="Helvetica" size="3" style="font: 12.0px Helvetica"><A href="mailto:owen@nerdnetworks.org">owen@nerdnetworks.org</A> (Owen B. Mehegan)</FONT></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><FONT face="Helvetica" size="3" style="font: 12.0px Helvetica">'Therefore, since brevity is the soul of wit,</FONT></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><FONT face="Helvetica" size="3" style="font: 12.0px Helvetica">And tediousness the limbs and outward flourishes,</FONT></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><FONT face="Helvetica" size="3" style="font: 12.0px Helvetica">I will be brief.'</FONT></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><FONT face="Helvetica" size="3" style="font: 12.0px Helvetica"><SPAN class="Apple-converted-space"> </SPAN>--William Shakespeare</FONT></DIV> </DIV><BR></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">_______________________________________________</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">mythtv-users mailing list</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><A href="mailto:mythtv-users@mythtv.org">mythtv-users@mythtv.org</A></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><A href="http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users">http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users</A></DIV> </BLOCKQUOTE></DIV><BR></DIV></BODY></HTML>