Backert Labs Rhumba preamp

I am thinking of going to an active line stage for sometime now. I have a separate thread for that and people have suggested some good choices. The reason for this thread if that, while I have all along said that  don't want tubes in the system, a few have convinced me that I should try tubes in the system, especially with ProAcs.
With that said, I researched a few tube preamps, that have XLR out and the Backert Labs Rhumba is the one that has only 2 tubes, which makes me comfortable to "deal in tubes".

I would like to hear from Backert Labs Rhumba owners who moved from Solid State preamplification to this preamp. What are the differences you heard? Any improvements?

I read a review on the Stevehoffman forum and the user mentioned that there is a "hum" in this preamp. This bothers me and hence I decided to check on this forum, if anyone has experienced this with the Rhumba in their system. One poster on this forum also confirmed the "hiss":

So I was wondering, if there are any users who have recently purchased this preamp and what is their experience with the hum/hiss issue.

BTW, I blame Ralph of Atma-Sphere, Almarg  and my dealer for making me consider tube amps :-) Can't believe I am creating this thread.

as a Backert Labs Rhythm user myself, i can highly recommend their fantastic linestage. i upgraded from Rhumba to Rhythm . From experience, the simpler the design the less problem you encounter from it, and the more easier to solve if any. It also doesn't necessarily mean a balanced connection or a fully balanced design circuit (i.e MP-3) will give you lower noise or have any advantage over single ended design. Fully balance design circuit will also susceptible to hum problems too.
 i'm being a BL user for 2.5 years and quite familiar with their pre. so if you need any advice about Backert Labs pre, feel free to ask .
@philipwu   How would you characterize the sonic difference between the two Backert line stages?
Thank You @audiothesis and @philipwu 

@philipwu ,
Do you have the Rhythm 1.1 or the 1.2? Like hifiman5, I would like to hear about the differences between your Rhythm and the Rhumba that you previously owned. Now was that Rhumba 1.1 or 1.2?
One question - when I think about tubes and the demos at audio shows it was always some vocals or smokey jazz or classical. But I do occasionally listen (and I am not bashful about it) to Michael Jackson, George Michael, etc - so pop from 80s/90s. My kids do sometimes come into the room and listen to the current pop like Justin Beiber, Uncle Kracker, etc. How does this kind of music sound with tubes? With my TVC, it sounds pretty transparent and clean. Does tubes make this kind of music sound "slow and syrupy"? Will I have to keep switching between the tube preamp and the TVC to get best of both worlds? Mind you - I listen to female/male vocals, classic rock, jazz and classical 80-85% of the time.