Schiit Freya S or Freya +?

The difference between the two stated components is that the Freya+
features a tube stage as well.
So three Pre-Amps in one.
Passive / Differential Buffer (SS) / Tube Stage.
Freya+ is promoted as "Refinement" over the previous generation.
Using the ’Tube Gain Mode’ was important for me when I owned the first
generation Freya / Vidar combo.
I don’t think that Bass would change due to any particular Pre.
Except for any sound difference between tube and SS.
Still relying on Schiit for my Headphone Gear ... Valhalla 2 / Mjolnir /
Gungnir,Multibit and Delta-Sigma.
In my experience.
I will say that the Bass is handled much better with the Schiit DAC’s.
My suggestion would be to look for a used SS Pre that would complement the level of the Reference 1000 Mono-Bloc’s.
I think that the ICE Power Amplification is well worth building on.

There is an audiophile on youtube that reviewed the original Freya.  He goes by the handle "Thomas & Stereo" and thinks the Freya gives him 90% of what his $3500 preamp does, at 1/5th the price.

https://www.youtube.com/watch?v=LwMXMtSprxI

Now the Freya+, with several refinements and spec improvements will do even better than that.  I don't have deep pockets for audio these days, but I'll be picking up the Freya+ by the end of the year.  I really don't think one can go wrong with either Freya version, but I want the XLR connections for my Gungnir DAC.  

I have the original Freya which offers three choices: passive, JFET buffer, and tubes with 12 dB gain. My source is the Oppo 103 out to a Schiit Modi Multi DAC. I MUCH prefer the tubes. Highly recommend the Freya. It makes MUSIC.

Tom

PS- bass is definitely more "organic" with the tube output...