Replace C28 with... ?

In my previous thread regarding a power amp, some of you commented that replacing the McIntosh C28 preamp would make a huge difference. However, what was missing was any elaboration how why you made the recommendation, and with what to replace it.

So, let’s get down to it.
McIntosh C28
HiFiBerry DAC+ Pro (Yes, I know... sacrilege, but it’s all I’ve got for now)
Bryston 4BST
Dahlquist DQ10
Polk PSW650 sub

Need guidance from you guys on whether I ought to be looking at SS, Tube or even a Passive unit. Since I have some skill with a soldering iron, I'm not above entertaining the idea of a kit.

I’ve seen the Tortuga LDRx and that concept looks pretty interesting. My worry is that the DQ10s can be a bit aggressive on the high end with that ribbon tweeter, so I’d like to hear your thoughts.

Thanks again in advance!