^

Thanks, Johnny (Cactus Music). This makes sense to me and seems probable that this has happened. For the M-Audio device, Phantom is either on or off for the front panel jacks (set using a switch on the back). The power is not specific to the different jacks. As I often practice in hotels or on the road, it seems entirely reasonable that I plugged an electric guitar into one of the front panel jacks directly without turning of the Phantom Power using the switch on the back.
 
Mike,
 
The manual for my compressor actually gives the order of operations for plugging in the DBX and says it needs to be off while plugging or unplugging anything.
 

DBX 162SL Manual
When connecting the 162SL, refer to the following steps:
• Turn OFF all equipment BEFORE making any connections.
• Mounting the 162SL The 162SL requires a two rack-space height (3.5 inches) and a standard 19 inch rack-space width. It can be mounted above or below (leaving 1U of space above and below the unit)  anything that doesn’t create excessive heat.  This is to ensure proper ventilation. Ambient tempera- tures should not exceed 113°F (45°C) when equipment is powered.
Caution: Never remove the cover. There are no user serviceable parts inside.
• Make connections via XLR or 1/4” connectors.
• Plug in AC power cable and power ON the unit.

 
I couldn't find anything like this for the RME UCX. It doesn't say 'turn off the device before connecting anything'.

Hi Geoff,
 I apologize for causing confusion.
 
 I hadn't even considered the potential for irony. I was speaking about a large Air Compressor in my work shop. It was switched "on" when I plugged it in and the voltage arced across an old dirty female plug... then the current literally melted the male pin off the compressor's power plug. It looked like it was a welding rig.
 
 It just happened last Friday. I fixed it Saturday. It was fresh in my mind and that is why I mentioned it.
 
 :-S

Bummer, Mike! I guess I just had musical compressors on the mind. I've been pouring over the manuals and looking for the info. Obviously I'm very interested in not having my current interface go bad on me.
 
Totally off the subject...
Mike, I also learned that you can use a number of RME interfaces together. I thought this sounded very interesting when it comes to expanding capacity.

mike_mccue
I hot plugged my air compressor into an extension cord last Friday.
 
White blue sparks spit out of the connection as the compressors plug was disintegrated by the arcing current.
:-)

Gotta learn to put the coffee cup down before reading your posts...
 
I can picture those sparks - not that I have ever done anything like that<G>!

gswitz
My M-Audio Interface is this one... Fast Track Ultra

 
Sorry, that one was after my tenure there. I can make a couple guesses, but that's about it.
 

gswitzThe Pres make noise all the time... when phantom is on or off. When nothing is plugged in. when the inputs are set to the front.
When inputs are set to the back, it works fine.
Lights appear to be working.

Making sure I understand...
when you plug something into a rear jack you get audio, pretty much as you'd expect
At all other times you get noise.
 
If that's the case then the problem is isolated to something that is not shared between the front and rear input jacks. Not sure what that would be, but the actual gain stages and such are all OK or the rear jacks would not work.

gswitz
I've taken it apart and didn't see anything obviously wrong.

Well that stinks! Or at least makes it a bit more challenging...

gswitz 
I don't really use it anymore. I have a new RME UCX which works great.

Well not to sound disloyal, but f you have an RME why are you still using the M-Audio? I have no issue with the gear that M-Audio makes, it is (my opinion, trying to be unbiased) as good as it gets at the price point. But the RME is in a whole different league!

I use the m audio spidf outs to get to ten inputs. Mostly, I use the rme and spidf to my tascam 2488 which gets me to sixteen inputs recorded at once.

I would sell or gift the m audio if it worked properly.

understood!
 
Well, perhaps you can gift it to someone that knows how to fix it? Just a thought...
 

Yep. Thanks for all the great tips on how to keep from messing up my RME. I'll be careful not to plug in a dynamic with phantom on.
 
Thanks to everyone who chimed in!

Some people still believe that leaving devices on all the time is good.
The opposite is true: heat kills components. (I am not talking about not using gear for years.)
 
I don't think you did anything wrong. You can try to send the interface in for repair. If it costs too much to repair, let them throw it away, and enjoy you RME interface.
 
Wilko