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.

@1markr ,
You are welcome. Good to know that you liked the Rhumba so much, as to not return it.

@soix ,
You are more than welcome to add to this thread. While I blame Ralph for getting me to start looking into tubes, I want to "wet my feet" first. The MP3 may be really good, but is currently out of my price range and also comfort (no. of tubes) range. Don Sach's SP14 looks good, but not on my list. Thank You for sharing.

I have decided to reach out to Backert Labs with my specific questions. But one point on their site that concerns me is - " A side-effect of using a single gain stage is that our models invert phase.". The link to that page is missing.
HI Milpai - I too know Bob for many years and have found him to be a gentleman of the utmost character.  His preamps are wonderful and an absolute bargain in terms of what they sound like and how they are built.  Phase inversion is not a problem- to compensate, you just switch plus and minus at the speaker input to revert to being "phase correct" for the purists, although many recording engineers do not pay attention to absolute phase.  Good Luck!
@jwpstayman , thanks for pointing that. But I managed to talk to Andy at Backert Labs and he answered all my questions. Looks like the new Rhumbas do not do phase inversion issue, since a transformer that they use inside does it (not sure if I put it the right way, as Andy explained).

I am impressed how much time Andy took to answer my specific questions related to hum, phase inversions, tube life, volume control, etc. Andy also told mentioned about a very good upgrade path for existing users. Besides the Parasound JC2 and Jeff Rowland Capri S2, I think I will seriously consider the Rhumba as a preamp upgrade. Frankly this is probably my number one preference for now.
The MP3 may be really good, but is currently out of my price range and also comfort (no. of tubes) range.
@milpai The Rhumba is a line stage. If you get the MP-3 as a line stage, it only has 4 tubes. The remaining tubes you are probably thinking about are for the optional phono section. The MP-3 has a polarity inversion switch.

Since I know Andy really well, and sorta know Ralph as a former customer, I won't go on in any detail here, but wanted to point out that it's pretty cool that both the Backert & Atma-Sphere gear is voiced by performing (in Andy's case -- professional) musicians. That may not matter to you, but I think it's cool and perhaps relevant. Cheers,