• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

AUDIOPHONICS MPA-S250NC Amp Review

Rate this amplifier:

  • 1. Poor (headless panther)

    Votes: 5 1.7%
  • 2. Not terrible (postman panther)

    Votes: 11 3.7%
  • 3. Fine (happy panther)

    Votes: 120 40.4%
  • 4. Great (golfing panther)

    Votes: 161 54.2%

  • Total voters
    297

JeremyFife

Addicted to Fun and Learning
Joined
Jan 8, 2022
Messages
707
Likes
793
Location
Scotland
I'm having a (what I think is a Grounding) issue with my Audiophonics MPA-S250NC XLR amp, connecting to my active sub's speaker level inputs (RSL Speedwoofer 10s).

Setup: Source = PC > Duok U2 PRO XMOS XU208 Digital Interface > Schiit Modi DAC > Schiit Loki preamp > Schiit Vali2+ headphone/preamp > Audiophonics MPA-S250NX XLR Amp > Speakers (RCA/Banana Plug from Amp's Output)
> RSL Sub, Speaker Level In (Spade Connectors also coming from the Amp's same Output)
  • When I make the connection to any of the Sub's Speaker Level Inputs I get a significant, constant humming from the subwoofer. I am reasonably sure this is a grounding issue.
  • It occurs even when the amplifier is Audiophonics amp is powered off
  • Both the sub and amp are connected to the same outlet (power strip)
    • I tried connecting the sub to an entirely different outlet, issue remained
  • I was using a different amp recently that has a dedicated sub out (RSL ia255.1) without any hum, I just tried upgrading to the Audiophonics and from my research this spade connection to sub speaker level in seemed like the simplest way to connect my sub. I don't have any other available connections on my preamps in this setup.
Since discovering the issue and doing some research, I'm reading that some Class D amp's black speaker terminals are not actually grounded, rather both terminals of each output are active. Is this the case with my Audiophonics amp? If so this means I have a grounding issue, is there an easier/cleaner solution than buying a Line Out Converter?

View attachment 357802

View attachment 357801

Thanks in advance!
What happens if you just take a line out to your sub from the pre-amp?
 
Top Bottom