How about this, for a 3065X low beeper volume solution... Setting up a full laptop, via USB, and running EasyDMM is a solution, yes? What about using a Raspberry Pi Pico to build a smaller USB dongle type of solution. I am not much of a coder, myself, but maybe someone could suss out how to just access the EasyDMM beeper signal. Since it is Siglent's problem, I think they should be willing to disclose how to code accessing that one function... The beeper signal in EasyDMM, that is...
Or, Siglent could add a select-able beeper function to the firmware that outputs a USB signal in a common code format. That seems like what Siglent would be more willing to do... And, we could easily DIY a solution with any USB capable MCU... The PIC18F4550 has on-chip USB. The Arduino Uno has on-PCB USB.
Hmm... We really don't need that coded in some USB language, I guess... Just make the USB Data out pin high when there is continuity and have any old MCU monitor Data out pin? As said, this is outside of my knowledge base.
If someone wants to look at the USB Rx/Tx for this application, I would be glad to send you one of my DIY USB2.0 Tappers. It allows you to easily access (tap) and/or break each of the four legs of USB2.0 = +5V, Data-, Data+, GND, free of charge. Requires your commitment and USA/48 address... Your choice of bare board, kit, or assembled.
If that person would also be willing to use a PIC18F4550 (which is the better choice than an Arduino, IMO, for this application) I would be glad to also send you one each of my Sandwich Bread and Lunch Break PIC18F4550 demo boards (Think Pinguino.) The Sandwich Bread plugs into a breadboard. The Lunch Break includes two breakout sockets, per pin. Both have 20MHz oscillators and USB2.0(B) connectors. Also free of charge. Requires your commitment and USA/48 address... Your choice of bare boards, kits, or assembled. The boards are PIC18F45K50 compatible, too. Includes one chip, 4550, or 45K50.
If MCU USB compatibility is not needed. I also have lots of other PIC demo boards.