How much do I need to spend to get a preamp that sounds better than no preamp?

Ok. The Arye preamp sounds better than no preamp to me. Finally!

Will try out the Belles ARIA preamp shortly, and evaluate whether it can wring out even more potential from my Belles SA30 poweramp. Currently the SA30 is direct-connected to a SOtM sDP-1000 DAC/preamp, but I suspect the SA30 is not firing on all cylinders here. For a while I’ve been a rather devout "no separate preamp, thanks" fellow, being that I’ve found it generally requires a pricey separate preamp to pull itself from the sonic equation (i.e.: transparency), so to speak, will bringing to the picture the qualities a capable separate preamp can deliver, like a livlier, more dynamic and firmly anchored meat-on-the-bones presentation. In addition to likely giving the SA30 more optimal "working conditions" with the inclusion of the ARIA preamp, there’s also the potential upside of by-passing the internal volume control of the SOtM DAC/preamp, of course only to be relieved by the one in the ARIA. 

Why the ARIA? It would seem to defy my preconception about requiring a costly preamp to make it worthwhile (i.e.: the ARIA retails for under $1,500), but several I know have pointing to it being extremely capable, despite its relatively low cost. Moreover Dave Belles is an excellent engineer with a particular knack for making rather authentic sounding amps - to my ears, at least. We’ll see how it turns out.

Cost for adding a proper preamp? depends demands of the system.

1.  A low-end system with no PreAmp would benefit from a $300-500 preamp. (eg. Schitt Lyr 2, tubed)
2.  Mid-end system: $500-1500 (several on the market)
3.  Hi end: $1500 on up, the skies the limit, but $1500-3000 should suffice for many systems that are not the crazy expensive hi end stuff.

this wonderful pre was just listed. I had one over a decade ago. Fully balanced with phono, but old school- no remote

https://www.audiogon.com/listings/lis9100g-klyne-audio-arts-7lx-3-5-solid-state

No preamp is still a preamp. It’s just built into the device.  

Generally a good stand alone preamp fed by the line level output of your source will be better than an amp fed directly by the volume controlled output of your source.

FWIW, devices that only include line level outputs are less complicated, have better interior layouts, and sound better than “do it all” devices that include direct volume control capability.  

It’s really pretty much about the two methods of volume control.  My ET7 and my SP20 pretty much whoop the volume controls that are available to me using any of my $2k level sources.  I’m better off feeding undegraded line level into either SP20 or ET7.  Same was true with ET3SE or PV8 or PV11.