AMP/DAC to replace Micca Origen G2?

Hello, I am looking to replace my Origen G2 as it has a broken potentiometer and plays full volume on the right channel only.

I have a pair of BD DT770 pro 600Ohms headphones and a pair of JBL LSR305 powered speakers. I am currently using the front 6.3mm out for the headphones and the rear 3.5mm for the speakers, although the LSR305s can also use XLR. I love the ability to toggle between them with a switch as opposed to both playing simultaneously.

Optical in would be nice since I had a lot of noise when using USB.

A knob for volume control for both outputs is a must. Any recommendations?

I have a Yamaha AG03 (mk I) I am using with my Beyerdynamic MMX300 (also 600 Ohm drivers).
It does not have optical though. Tested working with Windows and Linux (Steamdeck OS/Arch) and Debian).

You did not set a budget, a reasonably priced option from SMSL would be:

I’m using the Schiit Hel which may satisfy your requirements:

It has the front and rear outputs you’re currently using except that it automatically switches to the rear outputs when the headphone is not plugged in.

I’m using Grado headphones which are 32 ohms. Your 600 ohm headphones are harder to drive so the power output takes a hit down to about 100 mW RMS. The sound quality and loudness levels with the Grados is very good.

I’m using the USB DAC inputs, but it does also have a rear optical input.