pwstereo

Do you have another output stage you could try? Perhaps a pair of active speakers or an amp and speakers? You've eliminated the headphones already by substitution testing. So work back down the chain, substitute something in place of the Matrix M-Stage. It seems like you've eliminated the source and DAC from the quation when you tested disconnecting the M-Stage from the DAC and still had buzzing. I wonder which end of the RCA lead you disconnected? If it was the M-Stage end you've eliminated the RCA lead too. It seems like either the M-Stage itself, or it is being upset by some external source of interference. Is your mobile phone near the M-Stage or anything like that? Maybe move the M-Stage to another room and different power point and listen with headphones and no source connected to try and eliminate either something in the room or the M-Stage.

The good thing about low bass is that there isn't much directivity. Port and driver direction shouldn't be important. Driver or port close to floor tends to add additional bass level. Some subs are on short legs and fire downwards, I'd imagine that might work with some sofa designs. I suspect the port shouldn't be as close to the driver as is shown in your drawing. Two smaller drivers may help you keep to the armrest dimensions and proportions more easily (2 x 8" or 10"). You could have the driver/s on the rear panel and port at the front as you've shown. Have a look at some online sub box designs for the driver you want to use, then squeeze the proportions to suit your armrest shape while keeping the internal volume and port volume the same.

I like Amazon for the large number of music related shows.

Raspberry Pi, Volumio, and the Volumio app on a phone (or browser on any device). Little bit of setup, but a good solution with good customisability. You can get a screen for the Pi, but Volumio is made to run headless.

@thathifiguy This page explains it well. https://kb.roonlabs.com/Roon_Optimized_Core_Kit

That seems like a misuse of terminology. "In an electrical system, a ground loop or earth loop occurs when two points of a circuit are intended to have the same ground reference potential but instead have a different potential between them. Ground loops are a major cause of noise, hum, and interference in audio, video, and computer systems." Source, Wikipedia. The function of a shield is pretty well known I think. "The shield acts as a Faraday cage to reduce electrical noise from affecting the signals, and to reduce electromagnetic radiation that may interfere with other devices (see electromagnetic interference). The shield minimizes capacitively coupled noise from other electrical sources. The shield must be grounded to be effective." Source, Wikipedia.

@emanIf you're stuck, pm me and I'll do it for you.

Or you could get a copy of Snapseed for your phone. It will let you crop and resize images as well as many other typical photo editor operations.

Are you using a computer to do the avatar change?

I think there's an opportunity for artisanal, audiophile head braces 🤣

A switch with trim resistors or similar would be nice, to equalise levels between inputs. So a minimal passive preamp, individual volume trim for each input and a master volume for listening level control. Perhaps with the moden LDR opotocoupler designs (ala stereocoffee) this would not degrade the signal.

As long as you also have a clipboard, definitely.

Obviously it's a star sign. This week the Sun will be in Uranus and you'll hear more acutely than the lesser star signs. Make the most of this heightened awareness by doing some DAC testing. Later this week you may meet a dark and mysterious USB cable.

Oh dear, Countach

Lamborghini Coutach, even though I didn’t know how to pronounce it.