Whirlwind ISOXL Line Level XLR Inline Isolation Transformer

These things do the job we need them to, very well. Ours is an older church building with AC currently supplied from two different panels (stage and balcony). Grounding problems always. Yes, a bit pricey, but a lot cheaper than having to redo a nearly 70-year-old electrical system ($100k++)

These seem well made to me, though I don't know where the transformer comes from. Could be an OEM USA or elsewhere, but it seems to keep the integrity of the signal. I use these in my studio between my interface line outs and my monitoring station. They have taken the significant noise I had down to nil. Testing back and forth it seems to me that the signal is 95-99% intact sound wise. The only product I would imagine to do better in this regard is the Jensen P0-2XX. Their transformer designs are the most incredible in existence, in my opinion, for audio applications requiring transparency. That unit is also $135 per channel. These Whirlwinds are only $48. I also use these to block DC phantom power that might accidentally be turned on when using a channel strip as an insert in a mixing session. Fluke tests confirm that the transformer does indeed not let phantom power DC through, though I don't know the stress factor on the transformer of the Whirlwind nor the output of the channel strip at that point. I would rather they be stressed than the capacitor coupled outputs of a very expensive interface.

Well...if i were to judge its effectiveness from 1 to 10.....10 being perfect. I would say its effectiveness is a 7.5 It did indeed knock out the majority of hum as a result of a system gnd loop, but not completely. This is very difficult to do though. Would recommend.

Did not even lessen the static feedback one bit. Useless to me.

They're a little expensive, but if your frustrated with that radio frequency buzzing coming out of your PA speakers, these isolators do the job of affectively removing that annoyance. A couple of these in my front of house speakers really cleaned up the noise. They're WELL worth the price.