Help recommend a good tube preamp

Any opinions of the sonic differences between these similarly priced tube preamps:

Backert Rhythm 1.3

VAC Renaissance Mk V

Sorry for the repeated questions: it is difficult as auditioning such hard to find pieces is not possible (without buying from manufacturer with a view to audition - which I feel is a bit cheeky).

Haven't looked at all of the responses but you should check out Linear Tube Audio's preamp.  It is an ideal option.  i have a customer who is running one with a Hegel amp and there is good synergy.  

An update on my search: TL/DR - I am a proud owner of a VAC Renaissance Mk V.

I ended up buying a Rogue RP7 to try out from a fellow Audiogon member. It sounded nice for its price. The issue I have is that I have a very high gain setup (my DAC output is 5.8V). The Rogue RP7 is a high gain preamp and my speakers are pretty sensitive (93dB at 4 ohms).

So, I thought I better try some low gain tube preamps.

ARC Ref 6 gain is only 12dB. However, a concern is that its high output impedance might not be a good match with my H30 amp. Also: the REF6 might be too forward for the Beryllium tweeters in my speakers.

I went to Xtreme Fidelity northern NJ. Tom Canavan was fantastic and I could not recommend him enough. He had the VAC Master with Briscati Monos on Tidal Agoria speakers. That would be the first time I’d be listening to a VAC tube preamp.  I had read a review in Stereophile on a older VAC preamp that was not flattering at all.

It was, surprisingly, not what I thought it would be. It sounded very linear and, frankly, the setup sounded quite similar to what I had at home. So, I took that off the list (while mentally noting that the sound at my home must be decent then).

I was about to purchase a Backert Rhythm 1.3 when I saw and ad for a used VAC Renaissance Mk V on Audiogon. Taking a flier, I bought it, expecting not to like it.

However, I was wrong. In my setup, it sounded fantastic. Big soundstage. Very natural sounding instruments. And very holographic (had good depth). Instruments like the saxophone had body (which my SS preamp did not).

I apologized to Tom. In retrospect (and this is a tall ask), if I had gotten a at-my-home audition, I’d have purchased a new Renaissance Mk V from him instantly as my preconceived notions were wrong.

I recommend VAC preamps highly now.

Good choice, enjoy 

can I just tag along on this thread. 

am looking for a pre. using a Primaluna Evo 400 and am currently demoing an atma-sphere mp3. I don't have a Backert dealer where Im at, so I'd have to blind buy, get it shipped international and fork out for customs fees etc. all in all its a bit harrowing to blind buy at such a price. 

Could someone with the backert preamp describe how it is in general? 

Is it more of a tubey, warm smooth sounding pre or tends more to the neutral, fast, immediate side?

The MP3 has that warmer sound with great bass and mids. seems like the opposite of the Primaluna preamp.