Low buzzing through speaks

@kingbr OK are you ready to solve your problem? I think the high gain of the XLR connection or amp/preamp combo gain is your issue. A 10 db attenuator will kill that.  You might have to use a XLR to RCA adapter to make it work in your application. I'm 99% sure that is what your issue is.

Be sure to read this: A Discussion About Idle Hiss – Upscale Audio

I am going to disconnect XLR’s and try the RCA’s first thing in the AM. Then I’ll try connecting the wire for the ground between the Mac and Sim…

If you have the RCA option, that will be 3db down and might solve your issue, if not see above. 

@kingbr

Darn it, I just noticed this in one of the reviews of the Hosa ground lifter. The thought of this occurring just hit my brain, and only then did I dig a little deeper and realize someone else had the same concern as I. From a review of the Hosa:

I am VERY disappointed with this product. I bought two of these to use for my studio monitors when trying to debug ground loops, and discovered way too many problems for such a simple product:

== Wired incorrectly ==
First and foremost, this "ground lift" adapter doesn’t even lift the ground... The metal housing is electrically connected to the housing of each each end via the screws on either side. This would be less of a problem if it weren’t for the fact that the connector housing ground is connected to the ground *pin* on both sides. What does that mean? This is just a M to F XLR coupler. Which XLR cables never need.

I fixed this by opening them up, and de-soldering the wire that connects the ground pin to the connector housing. This was not a single mistake; BOTH units had this issue. Unless this is fixed, these are nothing more than a placebo.

I’m really sorry about this. This is frustrating, because I can make exactly what I need in a matter of minutes. I think the Pro Co model is more correct, as it looks like they’re disconnecting one end of the shell from the other (with shrink wrap), which breaks the metal shell ground connection (and pin 1 connection). Sorry, I know this is getting a bit technical now. The problem with the Hosa model, as mentioned above, is a ground connection is still taking place, which rides on the metal outer shell, even though the connection between pins 1 and 1 (on each end of the connector) are disconnected. This was something I was hoping the Hosa model didn’t do. Someone at Hosa designed their product poorly and incorrectly. Yeah, it happens.

Pro Co GLX In-Line XLR Ground Lifter Adapter

Checking stock, it looks like almost everyone on the internet is out of stock on this model (maybe because this one is designed correctly, and actually fixes problems). I’d call Parts Express to see if they can confirm that they actually physically have these on their shelf (the website says they have two in stock). @kingbr private message me with your address, and I’ll make one that I know works, does exactly what I want it too, and I’ll send it to you.

@russ69 I will admit, some people can describe hiss as buzzing, and confuse the two. So without me sticking my ear against kingbr’s speaker, I can only go on what he’s describing - that he hears a buzz.

Holy $h!t! Wow I just saw all this @russ69 thank you! 
 

@dpop thank you isn’t even nearly enough-I just ordered the last 2 @ Parts Express via the link you sent. I just got home and heading to bed and saw this. Without even looking into it I went and ordered the last 2😂, even after reading that article from Upscale that @russ69 referenced (very powerful article man-thank you). Have to get to bed but will follow up later after some sleep…

Thank you all and @dpop your generosity is off the charts…I’ll pm you later, thank you👍🏻 for your incredibly generous offer!