Would There be a Significant Difference

Over the past nine months I have acquired a new system, consisting of a NAD C568 CD player used as a transport, an iFi Zen Stream, a Schiit Bifrost 2/64 DAC, a Rogue Audio RP-1 preamp, a Benchmark AHB2 amplifier, all feeding into Fyne F702 floor standing speakers and a Definitive Tech Supercube 6000 subwoofer.  All inter-connected with modest but decent cables and using modestly upgraded power cables and power conditioning.  The improvement over my previous NAD 356BEE driving a McIntosh MC2120 driving a pair of Infinity Modulus EMIT satellites and the same sub is simply astounding.  Great sound stage, instrument placement—imaging, clarity, and lack of noise.  I know that most of the improvement in what my old ear hear is due simply to the higher grade products I have, but I also wonder if some of what I like is attributable to the fact that the RP-1 is a tube preamp.

However, my “advisor” says I should really have a better preamp, one at roughly the same level as the Fyne speakers (the 700 is series made in Scotland, with multiple layers of plywood vs MDF) and the Benchmark power amp.  Should I choose to upgrade my preamp, I would like be able to use the XLR connections from DAC to preamp to amp for even a bit lower noise—more prevention than an issue.  Our house is very quiet.

I have looked at and researched preamps up to about $5500, and I have narrowed the choices down to the following preamps:

Benchmark LA4/HPA4

Rogue Audio RP-7

Backert Labs Rhumba 1.3

Bryston BP-17 Cubed

Parasound JCP2 BP

PS Audio BHK Signature—normally out of price range but on sale (2B replaced?)

Are there other models in this price range that I should consider? I will purchase a separate phono preamp as necessary.

So, my question is, if I spend the money for one of these preamps, ranging from about $2500 to $5500, will I notice a significant improvement in the sound quality? Secondarily, would folks recommend I stay with a tube model or go with one of the two SS models, the Benchmark or the Parasound?  
 

Fortunately, AudioAdvisor and Benchmark have audition provisions, which will allow me to listen to all but the Backert and the PS Audio.

Any and all advice and recommendations will be most welcome.  I would not want to spend several thousand dollars on an upgrade that brought only marginal improvements, but I am willing to spend it—the kids are long out of college with no debt—for a significant improvement.  I’m one of the types who thinks you can get 85% (or so) of the best quality for a fair bit less than 85% of the cost. 

Thanks to all for any input.