Balanced/unbalanced audio input with unity gain

[belzrebuth]

Hi,
Is there a circuit that does that?
I just want for the output signal to always be what the input is.
I modified a Douglas Self circuit to be unity gain when there is an unbalanced or balanced input signal present but I don't want to flip any switches..
In this case I'd like some other switching element or another trick to flip this switch automatically when the ring connector is at GND potential?
Is this even possible?
I want to use TRS jacks that accept both balanced/unbalanced sources without level dropping that's why I need this.


edit : To my understanding I can't use any kind of switching connector either because those typically do their thing in the case of whether a plug is inserted or not while in my case I need to somehow detect if the ring is at GND potential (unbalanced) or not (balanced).
A comparator probably won't do anything either because an AC signal (audio) passes thru zero at regular intervals.
I thought about rectifying the incoming audio at the ring terminal (cold) and have a positive DC signal if a signal is present or think about some other hacky solution but I'll probably wait for a smarter tip..

[RFDx]

Like you suggested, use a TRS (6.35mm) stereo socket. Tip to the non-inverting, ring to the inverting amplifier input and sleeve to ground. A TRS stereo plug for balanced (tip + ring) signals but a mono TS plug for unbalanced input signals.

[belzrebuth]

I failed to mention that input will only have 2 TRS sockets so it has to accept both balanced and unbalanced with no level drop.

[RFDx]

I failed to mention that input will only have 2 TRS sockets so it has to accept both balanced and unbalanced with no level drop.

Yes, TRS sockets for the inputs. The difference is in the plugs, TRS for balanced but TS for unbalanced. The TS plug automatically rewires the differential amplifier into a single ended version with unity gain.