Preamp or not.


I currently have the following setup Bluesound Node 2I, Topping D90, Pass XA25, Crites Type B speakers.
I originally had a Sunfire preamp but it failed. Then I upgraded my system last year. I tried a passive pre amp but removed it and now run the DAC direct to amp. The passive sounded fine but I ended up running it at full volume. No remote. I use the Bluesound ap to change volume. My thinking was less is better. My speakers are efficient and dynamic.

The Topping puts out 2V. Pass told me this is adequate. I am wondering what a preamp would do. How would it improve or degrade the sound? How much gain do I want from the preamp? Tube or solid state? Any other suggestions are welcome or should I just leave this alone? I don’t like buying, selling and failing. Here are some I saw that look interesting.

Pro-Ject Pre

Doge

Modwright

Van Alstine

I would like to spend 2000 or less. I don’t need Phono. Remote volume would be nice. Thank you again.

128x128daledeee1
you do not need a preamp but a good one can improve the sound greatly.  
it is not so much about voltage but clean voltage and robust power supplies capable of fast changes and that greatly improve drive and dynamics.  
the analog section of DACs and digital players are what separate the good from the great and as so with the preamp feeding the power amp. 
look at the Rogue Audio RH-5 Linestage Headphone amp.  Review in Stereophile.   

https://forum.audiogon.com/discussions/high-end-stereo-preamps-worth-it?page=2

in particular, see mike lavigne’s post on second page... it covers well what is being asked

search bar above is always your friend... :)
If you can stretch a bit you could consider a Sachs pre that’d likely sound glorious with your wonderful amp.  Best of luck. 
I would consider a preamp with some tone control.that way you adjust some of the older recordings 
I finally understand the volume thing and explains "sounds better if it's turned up".  Much thanks @mlsstl .  I hope I wouldn't get too sensitive with the volume meaning small adjustments equal big volume swings.  The extra power supply might be a tradeoff for sensitivity.  Is that correct?  The speakers I have are about 100dB efficient(or higher)