I've been having trouble getting a clean signal on this new equipment. Here's the chain...

CAD M9 tube mic > Focusrite VM Pro > Edirol UM-25 > computer Hard drive located in the next room. Pretty simple, yes?

The cabling from the Cad mic into the VM pro is a balanced XLR, and from VM Pro to Edirol is balanced XLR also.

Doing straight voice/narration I would expect a nice clean sound (using no compression or other processing offered by the pre.)

Instead, what I've been getting is a very noticable background "hiss" - sounds almost like tape hiss. This is in a small 7X10' sound-proofed room...no external noise coming in to explain this "hiss" sound. The computer is in the next room.

I am monitoring this on line level output to headphones, directly out from the A/D interface.

If I bypass the pre and take the mic directly to the Edirol A/D via balanced XLR, "voila", I get a very clean, nice signal with none of the hiss. The hiss goes away...no noise.

The sales guy where I bought the equipment suggested that there was some impedence mismatch in using an XLR from the mic to the pre and then from the pre to the A/D, and suggested I try using the balanced TRS patch cable instead.

I'm skeptical...wouldn't a balanced TRS give the exact same signal as a balanced XLR? Just different plugs...right?

I am beginning to think the Voicemaster Pro is defective. Just to be sure, I've ordered a TRS balanced cable that I will try, just to eliminate that possibility.

Does any of this make sense?

All ideas appreciated!

Thanks,
Joe