SPA1000 and DTA-2.1BT2 hum - speaker out to rca in

[Frankqa]

Hello,
I have a DTA-2.1BT2 and I wanted a little more power for the sub. I had an older SPA1000 laying around and figured why not.
The only problem is that I get a nasty hum from the sub when the DTA-2.1BT2 is turned off. I used a bare speaker wire to male RCA converter that I found on Amazon. I also have tried a pre-assembled shielded cable (male Banana to male RCA). In either case, I still get the hum. I have isolated the SPA1000 from the DTA by plugging them into separate circuits and there's still a hum. I've isolated everything else and put the SPA1000 in the place of my HT amps and I don't have a hum. The hum is in the subwoofer speaker out of the DTA to the RCA in on the SPA. So, I've heard I can remove the ground spade from one or both of the plugs or try to ground the DTA amp or SPA amp by connecting a wire from one of the chassis screws to the screw on the plate of the outlet.
Any advice would be greatly appreciated.

[Evil Twin]

This is not an unusual problem with the older SPA plate amp series; it has to do with common mode current flows in the actual ground system which in turn is dependent on the CMRR of all the components in your amplification chain.

This section of a page from the SPA500 manual highlights the problem and possible solutions. Only having single ended RCA input connections is an unfortunate flaw in this otherwise well built plate amplifier.





Solutions like this Neutrik NTE 1:1 isolation adapter with their connectors could be considered, if you can assemble this on your own:


https://www.parts-express.com/Neutrik-NTE1-11-Audio-Adapter-Transformer-for-NMxxx-Modules-092-2247?quantity=1&utm_source=google&utm_medium=cpc&u tm_campaign=19344435533&utm_content=144470248733&g adid=642323859525&gclid=EAIaIQobChMI8fKskODq_QIVcT StBh12qASCEAQYAiABEgKqMPD_BwE


or for a more "off the shelf" approach, consider products like this two channel one from Kopul

http://www.kopulcables.com/product/4388/Kopul-HMX_2-Humbuster-_-Dual_Channel-Hum-Eliminator-with-XLR-and-1*4''-Connectors