Susvara pre-amp and amp combination

Hello all:
I have a pair of Susvara's and am thinking about pre-amp/amp combo for this. I currently have the KECES E40 which has a sound I like. The rest of my equipment:
Denafrips Terminator II
Denafrips Hermes DDC
Magna mano Ultra MK II
i2s hdmi for all interdigital connections


Not a lot to go on here.  What’s your budget, and are you buying new or used?  What kind of improvements are you looking for vs. the Keces, and what sound characteristics are most important to you in headphone listening?

I am looking for excellent soundstaging, and a bit more definition than the E40.  Used is OK  I have found that I like a good bass without harsh high end. I realize that there are ongoing discussions of amplifiers for the Susvara but never any discussion of pre-amp. The Terminator has no pre-amp functions.

For my own Susvara use, I use an MSB Analog DAC which has a volume control, and an Eddie Current Studio B headphone amp, which also has a volume control but no remote, which the MSB does have. With the right tubes, Susvara sounds awesome through the EC....